Where Is Springfield?

[Jason Tandro]

What I have here is an excerpt from a VERY long document trying to deduce the state where the town of Springfield (from televisions The Simpsons is). It should be noted that this contains minor spoilers.

Read this or don't, but either way post below as to where you think it is.
(I'll post mine a little later).

---

Evidence for Springfield's location
Note: all Treehouse Of Horror stories, all couch gags, and episode [BABF19] Behind The Laughter are non-canon; that is to say, they do not form part of the main Simpsons "continuity". Evidence for Springfield's location from these sources is listed here for completeness, but does not count.
Season One
[7G06] Moaning Lisa
Lisa wails for the Iowa farmer whose land has been taken away by uncaring bureaucrats, and the West Virginia coal-miner. Mr. Largo explains that "none of these unpleasant people are going to be at the recital next week", implying Springfield isn't in Iowa or West Virginia.
[7G07] The Tell-Tale Head
Homer watches and listens to a football game before and during a church service. The earliest kickoff on Sundays is 1pm Eastern Standard Time, which suggests Springfield is in a time zone further west, most likely Pacific Time - unless the family is going to church at 1pm.
[7G12] Krusty Gets Busted
Kent Brockman reports that Krusty the Clown started out as a street mime in Tupelo, Mississippi.
Season Two
[7F03] Bart Gets An F
Springfield is far enough north to get snow (and for the residents to have plenty of snow-related equipment), but south enough that six inches of snow will close the schools. There are many other episodes which back this up.
[7F02] Simpson And Delilah
Homer's social security number is 568-47-0008, and the 568 prefix is typically issued in California.
[7F01] Two Cars In Every Garage, Three Eyes On Every Fish
The state flag has three horizontal bands, green above white above orange, and a blue star. The state motto is "Not just another state". Burns refers to the state capital as "down there" at his rally, so Springfield is north of (or uphill of) the state capital.
[7F05] Dancin' Homer
The Springfield Isotopes faced teams from Shelbyville, Salem, and Burlington. These would be towns and small cities from the same area as Springfield.
Capital City is (at least) 220 miles away.
[7F06] Bart The Daredevil
Bart attempts to jump Springfield Gorge on his skateboard a la Evel Knievel. Typically, gorges are cut either by glacial action or fast rushing rivers (see the Grand Canyon).
[7F13] Homer vs. Lisa And The Eighth Commandment
Bart watches the Top Hat Channel, which is not available in Florida or Utah.
[7F15] Principal Charming
Marge refers to a family trip to the Bowlers' Hall Of Fame in Saint Louis, Missouri. Springfield cannot be in Missouri. Also, the agency that distributes driver's licenses is called the "DMV". The ZIP codes (90701 and 90702) correspond to Artesia, California.
[7F16] Oh Brother, Where Art Thou?
OFF drives to Detroit, Michigan to meet Herb Powell. So Springfield can't be in Hawaii. On the way home, they pass a sign saying "You are leaving Michigan", meaning Springfield isn't in Michigan either.
[7F17] Old Money
Grampa crosses the state border to reach a casino. Springfield cannot be in Hawaii or Alaska, then, which are the only state with no casinos in neighbouring states (having no neighbouring states to speak of).
The ghost of Bea says, "I'm haunting a family in Texas." Not, presumably, Springfield's state.
[7F21] Three Men And A Comic Book
Michigan and Oregon are the only states that gave dime refunds for empty bottles at the time this episode aired.
[7F22] Blood Feud
Mr. Burns' letter to the Simpsons has both their address and his own written on it, but both are unintelligible.
A store in Springfield Mall sells items from Alabama. However, at least one reader has reported that you do indeed get Alabama-themed stores in Alabama sometimes.
Season Three
[7F24] Stark Raving Dad
Route 401 (the Dalai Llama Expressway/Michael Jackson Expressway) passes through the city. The highway reappears in [8F17] and [8F21]. US 401 runs from approximately Warrenton, NC to Sumter, SC, where we believe it ends. Of course, it could be State Route 401...
Leon says "I'm a bricklayer from Paterson, New Jersey." Springfield can't be in New Jersey.
[8F01] Mr. Lisa Goes To Washington
In the Regional Finals montage we are shown a number of essay finalists reading essays in a number of states. Appearing as we pan across the map are Alabama, Minnesota, and New York - none of which match up with the state we pan over when we reach Springfield.
Springfield is near the south-east corner of a state that is landlocked on the south-east corner. Moreover, that corner is common to three other state corners. There is only one Four Corners in the USA, suggesting Utah. Unfortunately, the borders at the corners are crooked, whereas in the real USA, they're straight. And Andrew Gerber points out that that region of Utah is VERY desolate.
If you look closely you can see the state abbreviation "NT" as we reach it, though Rich McGee notes that the state abbreviation on the junk mail was "TA".
In this episode we also meet Springfield's congressman, Bob Arnold. During the photo-op and the bribe scene preceding it we get a good look at Springfield's state motto ("Not just another state") and seal: clockwise from the top left, these are a star, an ear of corn, a nuclear power symbol and a beaver.
The fact that Arnold was approached concerning the Mount Rushmore scheme doesn't necessarily mean he was senator for South Dakota and therefore also doesn't mean Springfield is in South Dakota. See the episode capsule for more details.
[8F04] Homer Defined
The map on which the TV reporters have marked the lethality zones clearly shows Springfield to be a city on the West side of the mouth of a river which flows South.
[8F06] Lisa's Pony
Burns asks Homer if he's aware of the state's usury laws. Nevada has none.
[8F09] Burns Verkaufen Der Kraftwerk
Horst informs SNPP drunks they'll spend six weeks at their drying-out facility in Hawaii, so Springfield can't be in Hawaii.
[8F10] I Married Marge
One of the frat brothers interviewing for Homer's job says he comes from the Alabama chapter of the fraternity. He would hardly specify the state if it was different from Springfield's.
[8F11] Radio Bart
Police Chief Wiggum mentions a piece of machinery in Shreveport, Louisiana, so Springfield isn't in Louisiana.
[8F12] Lisa The Greek
"In episode 8F12 (Lisa the Greek), Homer asks 'Who do you like in the afternoon games?' after the completion of the first game(s). NFL Sunday afternoon games generally go at 1pm EST and 4pm EST. So in the Eastern and Central time zones, both games would be afternoon games and the phrasing is out of place. The reference to 'the afternoon games' for those games starting at 4pm EST is suggestive of a location in the Mountain or Pacific time zones. The Sunday evening game often goes at 8:30 EST, which could also be called an afternoon game in the Pacific time zone (5:30 PST), but I don't know if it's commonly referred to as such, or as an evening game as it is referred to further east."
[8F14] Homer Alone
Marge stops her car on the Springfield Memorial Bridge, which bears more than a passing resemblance to the Memorial Bridge in Springfield, Massachusetts: see here. That seems like more than a coincidence, but on the other hand, how many other bridges look like that?
[8F15] Separate Vocations
Bart and Lisa's standardised tests are sent by plane to Iowa Non-International Airport, but this doesn't necessarily mean the plane was an interstate flight - Springfield could still be in Iowa.
[8F17] Dog Of Death
The state Springfield is in has a lottery, for which the odds of winning are 1 in 380,000,000 (i.e. choose 6 numbers from 83). The state also contains Swartzwelder County.
[8F21] The Otto Show
Otto's driver's license looks a hecukvalot like the California driver's license. Complete with the useless dot in the corner. (Yes, we know it's not useless.)
[8F22] Bart's Friend Falls In Love
Samantha says they moved from Phoenix, but doesn't say "Arizona". So they might be in Arizona...
Season Four
[9F02] Lisa The Beauty Queen
Lisa welcomes a boatload of immigrants in Springfield Harbour, only to learn that they're being deported. Springfield must have access to an ocean then, though possibly indirectly via a river or lake.
[9F06] New Kid On The Block
The Winfields decide to "run out the clock in Florida".
[9F08] Lisa's First Word
The waters near Springfield have sharks: while house-hunting, Homer and Marge look into buying a houseboat, and Captain McAllister is attacked by a shark while he's showing them around.
[9F10] Marge vs. The Monorail
Kent Brockman, while introducing guests at the monorail opening, points out a star from a show called "Springfield Heights 90210". The 90210 ZIP code is Beverley Hills, California, though, so either Springfield IS Beverley Hills (unlikely) or the show in question is a spoof of Beverley Hills 90210 (much more likely).
Lyle Lanley displays a map showing the locations in the United States of the towns of Brockway, Ogdenville and North Haverbrook. Assuming Lanley's map is accurate, which is far from clear, Brockway is in South Carolina, Ogdenville is in Arizona and North Haverbrook is in South Dakota or Nebraska. Later in the episode, Marge drives to North Haverbrook, and while it's implied North Haverbrook is near Springfield, it's never shown exactly how far she drives, so this doesn't really mean anything. However, these three towns will get mentions later so keep this piece of evidence in mind.
[9F11] Selma's Choice
Hans Moleman's driving licence is shown at the DMV. The licence is readable when paused. The address reads "Springfield, USA, 90701". This ZIP code corresponds to the cities of Artesia and Cerritos in California, placing Springfield firmly in California!
[9F12] Brother From The Same Planet
Springfield Gorge, also seen in [7F06] Bart The Daredevil, is apparently "the third most beautiful gorge in this state", which suggests gorges are indeed a common feature of whatever Springfield's state is.
[9F14] Duffless
We see a brief and highly informative shot of Homer's driving license when he gets it revoked. The state abbreviation for Springfield is NT again, while Springfield's ZIP code is 49007. This is the ZIP code for Kalamazoo, Michigan.
[9F17] So It's Come To This: A Simpsons Clip Show
Springfield isn't in Hawaii, as Homer offers to take the whole family there.
[9F18] Whacking Day
The following states are known to have "rattlesnake roundups": Texas, Kansas, Pennsylvania, Oklahoma, Alabama, Georgia and Florida. (Does anyone have a full list?)
[9F20] Marge In Chains
As Snake steals the Kwik-E-Mart, he passes a sign indicating that Springfield is 63 miles from North Haverbrook, which [9F10] Marge vs. The Monorail establishes is in South Dakota or Nebraska, so Springfield is in one of these two states.
However, the sign also lists Springfield as being 678 miles from Mexico City, which means it must be in Texas, Louisiana, Oklahoma or New Mexico, so Lanley's map probably isn't actually very accurate.
Season Five
[1F03] Marge On The Lam
If Chief Wiggum's remark about being directly under the Earth's Sun is correct, then Springfield must be somewhere south of the Tropic of Cancer - i.e., somewhere in Hawaii. Of course, we also have to take into account the fact that Chief Wiggum is an idiot.
[1F04] Treehouse Of Horror IV
The Simpsons go to Pennsylvania, placing Springfield outside of Pennsylvania (for this episode only).
[1F06] Boy Scoutz N The Hood
Reading the map of Krusty Burger outlets, Homer remarks, "Hey, there's a new Mexico!" implying Springfield is not in New Mexico.
Homer and Bart are swept out to the Atlantic on their rafting trip, which implies an eastern state, but we don't know how far they travelled before the trip began.
[1F08] $pringfield (Or, How I Learned To Stop Worrying And Love Legalised Gambling)
Marge suggests Lisa go to the geography pageant as Nevada "in honor of legalized gambling", but Lisa refuses. This kind of suggests Springfield isn't in Nevada. She goes as Florida instead, because she likes orange juice and old people, which, again, only kind of suggests Springfield isn't in Florida either.
[1F10] Homer And Apu
There are apparently no Kwik-E-Marts in Ohio, so Springfield can't be in Ohio.
[1F11] Bart Gets Famous
Springfield is not in Michigan: the Box Factory manager specifies that his boxes are assembled in Flint, Michigan.
[1F12] Lisa vs. Malibu Stacey
An executive at the Malibu Stacey factory calls in a favour from Washington, implying Springfield isn't in the District of Columbia.
[1F18] Sweet Seymour Skinner's Baadasssss Song
Bart and Skinner visit the beach - Springfield is either on a lake or an ocean.
Season Six
[2F02] Sideshow Bob Roberts
In this episode, Springfield Prison appears to be on an island that is similar to Alcatraz Island.
Springfield is also revealed to be within driving distant of Archie's Riverdale, wherever THAT is.
[2F04] Bart's Girlfriend
Springfield has a lighthouse commanded by Captain McAllister.
[2F06] Homer Bad Man
Abe sent the family a postcard from Florida, meaning Springfield probably isn't in Florida.
Abe also mentions that "I'll be deep in the cold, cold ground before I recognise Missoura!" so Springfield can't be in Missouri.
[2F08] Fear Of Flying
Homer's search for a new watering hole leads him to an establishment with a marked resemblance of the Cheers Bar, which is in Boston, Massachusetts.
OFF wins a trip to anywhere in the USA except Alaska or Hawaii. Bart asks to go to Alaska and Lisa to Hawaii. Springfield must be in neither of these states.
Homer says "We'll just wait for the killer bees to come to us", implying Springfield isn't in a state with killer bees. On the other hand, see the reference for [2F19] The PTA Disbands, below.
The airplane that Homer and Marge were in crashes into a lake or ocean on takeoff.
[2F10] And Maggie Makes Three
Homer promises Joey they'll make it to California someday. So presumably they aren't there already.
[2F11] Bart's Comet
Bart races Milhouse to Utah. Also, Springfield is represented by a Senator, meaning it can't be in Washington, D.C.
[2F13] Bart vs. Australia
The plane trip started at 13:30 Monday and ended at 06:45 Wednesday, a difference of 41 hours and 15 minutes. What the writers seem to have done here is added the largest possible time difference between an American city and an Australian one (19 hours, e.g. Los Angeles and Sydney) to the longest possible flight from America to Australia (~22 hours, e.g. Bangor, Maine to Perth). Unfortunately, given that both countries span many time zones, we don't know the time zone where OFF landed, we don't know how much real time their flight lasted, and that a situation like the one described above is HIGHLY unlikely to occur since it assumes Springfield is simultaneously on both the East and West coasts of America, there's no way to guess Springfield's time zone from these facts.
[2F19] The PTA Disbands
Fort Springfield was the site of a Civil War battle, suggesting it's in the southeast quadrant of the USA. The architecture at the fort suggests it's more of the type of Great Plains fort used in wars against American Indians. It was a Union fort since its troops wore blue.
Bart has found a hive of killer bees, and asks Milhouse to come and throw rocks at it. That puts Springfield in a state with killer bees, suggesting it's in one of the states which borders Mexico. However, if you compare this with the reference in [2F08] Fear Of Flying above which says Springfield does NOT have killer bees, the two references neatly cancel each other out.
[2F21] The Springfield Connection
Medfly spraying is done only in California.
[2F22] Lemon Of Troy
The lemon tree was not natural but planted by Springfield's founders, and so does not provide any clues as to Springfield's location.
[2F16] Who Shot Mr. Burns? (Part One)
Springfield is not in one of the states which once belonged to Mexico, since in those states, the mineral rights belong to the state.
Burns begins a slant-drilling operation. Slant-drilling is illegal in Texas. But on the other hand, Mr. Burns does many illegal things.
Grampa's earthquake preparedness suggests that Springfield is along the Pacific Rim, or perhaps in southeastern Missouri.
Season Seven
[2F20] Who Shot Mr. Burns? (Part Two)
Chief Wiggum remarks, "No jury in the world's going to convict a baby. Mmm...maybe Texas." Springfield can't be in Texas.
[3F02] Bart Sells His Soul
Milhouse moves in with his grandmother while his house is sprayed for potato bugs. "Potato bug" is a common name for a woodlouse, however, and woodlice are found all over the world. This doesn't narrow the search down at all.
[3F04] Treehouse Of Horror VI
Collapsing advertising mascots destroys Norman Vincent Peale's birthplace. That places the Springfield from this segment of this particular Halloween Special firmly in Bowersville, Ohio. (Note that THOH episodes are non-canon!)
Paul Anka's stop-the-monsters guarantee is void in Tennessee, which implies Springfield might not be in Tennessee, as the trick works. But who can say?
[3F05] King-Size Homer
Springfield has Daylight Savings Time. (Lousy farmers.) Unfortunately, parts of every state observe DST so this doesn't narrow things down much.
[3F06] Mother Simpson
The bird that lands on Homer's head is an American White Pelican; they are generally not found east and north of the Mississippi River valley and Florida.
[3F08] Sideshow Bob's Last Gleaming
Springfield has alkali flats and badlands.
Homer yells at Sideshow Bob, "Go back to Massachusetts, pinko!"
[3F07] Marge Be Not Proud
Mrs. Van Houten said Mechanicsburg without naming a state, suggesting that it's the same state that Springfield is in, probably Pennsylvania. There's a Mechanicsburg in Illinois, Indiana, Mississippi, Ohio, Pennsylvania, and West Virginia, but Mechanicsburg, Pennsylvania is probably popular enough not to need the state.
[3F09] Two Bad Neighbors
George Bush senior lived in the following states: Massachusetts, Connecticut, Ohio, Texas, Virginia, Maine. One might be able to add the following: New Jersey (Princeton), District of Columbia (not a state, but might count), New York (long shot. Bush lived in a suburb of New York City and met Barbara there).
[3F10] Team Homer
Springfield appears to be in one of the states where dress codes are legal.
[3F11] Scenes From The Class Struggle In Springfield
A sign on the highway mentions a former Japanese internment camp. Japanese internment camps were almost all in California.
Lisa infers that Ogdenville has a sales tax. However, Ogdenville's also at least 341 miles from Springfield. That's far enough to be out of state. (But see [BABF09] Saddlesore Galactica.)
Evelyn won't anything unless it's shipped overnight from Vermont or Washington state, implying Springfield is in neither of these two states.
[3F13] Lisa The Iconoclast
The 1796 founding date of Springfield would seem to put it somewhere between the Appalachian Mountains and the Louisiana territory, probably in the Kentucky/Ohio/Indiana region. However, they didn't have buffalo that far east. Buffalo were mostly on the plains, although Springfield is too wooded to be there.
Springfield was created before the Louisiana purchase.
Settlers mistook a phrase in the Bible and headed west from Maryland.
[3F15] A Fish Called Selma
Troy and Selma visit Route 18 Flea Market and Drive-In.
[3F17] Bart On The Road
From this episode we can rule out: California, Nevada, Utah (from the map), Tennessee, Missouri, and Georgia (the suggested destinations).
Jose Lafaurie adds, "Also note that when Bart calls collect it's getting dark in Tennessee but the day is bright in Springfield (you can take a peek out the window), and when Bart calls Lisa again, it's afternoon in Tennessee and early morning in Springfield, suggesting a Pacific Time Zone area for Springfield."
"Bart and the kids started their trip in a state with a lot of cornfields and prairies, which indicates a Midwestern state."
"If they visited Branson, MO, along the way, Springfield's state probably wouldn't be east of the Mississippi since they took an easterly (or southerly, at some point) route."
[3F18] 22 Short Films About Springfield
Superintendent Chalmers and Principal Skinner have a conversation about the phrase "steamed hams" which is allegedly from upstate New York, implying Springfield is not in New York.
[3F20] Much Apu About Nothing
Homer tries to locate Springfield on a map of the USA. He points to Chicago, but Lisa says Springfield is nowhere near there. This doesn't necessarily mean Springfield isn't in Illinois, though.
When Lisa points to where Springfield actually is, Bart conveniently walks in and obstructs the map with his head. However, from these two screenshots we can say it definitely ISN'T in Washington, Idaho, Oregon, California, Nevada, Utah, Arizona, Montana, Pennsylvania, Maryland, Delaware, New Jersey, New York, Connecticut, Rhode Island, Massachusetts, Vermont, District of Columbia, New Hampshire or Maine, because if it was, we'd be able to see Lisa's arm pointing.
Fat Tony tells Apu that in his new identity he was born in Green Bay, Wisconsin, implying Springfield is not in Wisconsin.
[3F21] Homerpalooza
Springfield is no less than 30 miles from Capital City. (It was 220 miles away in [7F05] Dancin' Homer.)
Season Eight
[3F23] You Only Move Twice
Cypress Creek is "upstate," suggesting a vertical state. Redwood trees (apparently endemic to Cypress Creek) are only found in the Pacific Northwest.
[4F05] Burns, Baby Burns
The conductor doesn't initially mention the state that Springfield is in, so presumably it's in the same state as the Harvard-Yale game. Larry offers "local cactus".
[4F06] Bart After Dark
Lisa says she wants to clean an otter at the beach; sea otters are only found on the west coast, indicating that Baby Seal Beach is on the west coast, and thus Springfield, in this episode, is near the west coast.
Marge says that Baby Seal Beach is a four-hundred-mile drive away. That puts Springfield within 400 miles of the US coast.
[4F07] Hurricane Neddy
Hurricanes are most likely to strike the east coast, typically beween North Carolina and Florida. However, Atlantic hurricanes can go along the Gulf Coast (Texas, Louisiana, Mississippi, Alabama) further in-land and further north. Also, hurricanes happen along the Pacific coast (California, Oregon, Washington State). Considering that Springfield hasn't had a recorded since 1977, it's actually unlikely then it's along somewhere between North Carolina and Florida since that is where most hurricanes occur in the United States.
Ned talks about people "back east."
This is one of several episodes depicting capital punishment by electrocution. States that do this are Alabama, Connecticut, Florida, Georgia, Indiana, Kentucky, Nebraska, Ohio, South Carolina, Tennessee and Virginia.
[3G01] The Springfield Files
Springfield is in the nation's heartland, according to Mulder when he reads the UFO sighting report.
[4F08] The Twisted World Of Marge Simpson
Oklasoft, "Oklahoma's fastest-growing software company", is mentioned by Edna. But there's no reason why Springfield might not also be Oklahoma.
Marge receives an order for 300 pretzels to Batavia, New York, but again, this might not count against New York - the person ordering the pretzels would be certain to specify the state if he didn't know where Marge was operating from.
[3G03] Simpsoncalifragilisticexpiala(Annoyed Grunt)cious
According to Principal Skinner, Boy sales are only legal in Springfield's state, and Mississippi.
[4F15] Homer vs. The Eighteenth Amendment
Jake Schultz notes that there are many references to Massachusetts and Boston in this episode. Unfortunately, they all appear to be purely circumstancial...
Homer says Marge isn't the world's worst mother, "What about that freezer lady in Georgia?" which implies Springfield is not in Georgia.
[4F16] The Canine Mutiny
The area code Bart fills in on his credit card application is illegible, but may be one of the following: 112 (does not exist), 503 (Oregon), 513 (Ohio), 518 (New York), 613 (Canada) or 618 (Illinois).
[4F17] The Old Man And The Lisa
The following states have 5 cent refunds: California, Connecticut, Delaware, Iowa, Maine, Massachusetts, New York, Oregon, and Vermont.
Burns catches some whales in his omni-net.
[4F18] In Marge We Trust
Homer, Bart and Lisa go to the library at 16:05 to call Japan, and the Tokyo plant is open when they call. Japan is 9 hours ahead of UTC and America is between 5 and 8 hours behind, for a difference of 14 to 17 hours, giving a local Japanese time of 6:05am to 9:05am. However, it seems plausible that the plant could open as early as 6 o'clock in the morning, so this doesn't really narrow down the possibilities for Springfield's location.
Season Nine
[5F03] Bart Star
Hank and his son Bobby from King Of The Hill appear. After his son's pee-wee football team loses to Springfield, Hank says, "We drove 2000 miles for this?", placing Springfield between 1500 and 2500 miles from their home in Arlen, Texas.
[5F13] This Little Wiggy
This is one of several episodes depicting capital punishment by electrocution. States that do this are Alabama, Connecticut, Florida, Georgia, Indiana, Kentucky, Nebraska, Ohio, South Carolina, Tennessee and Virginia.
[3G04] Simpson Tide
"kmano7" notes that in "Simpson Tide" Springfield harbour is clearly seen to be on the west coast of America. Though it's too hard to pick out a state, that narrows it down to Washington, Oregon or California.
[5F15] Girly Edition
The Union Pacific train comes through Springfield. Union Pacific operates in these states: Arkansas, California, Colorado, Idaho, Illinois, Iowa, Kansas, Louisiana, Missouri, Montana, Nebraska, Nevada, New Mexico, Oklahoma, Oregon, Tennessee, Texas, Utah, Washington, and Wyoming. And with its acquisition of the Chicago & Northwestern, we can add Minnesota, South Dakota, and Wisconsin.
[5F09] Trash Of The Titans
This is an extremely important episode, because at the end of it, the entire town of Springfield is moved five miles. That could potentially put it over a state line. References from all later episodes may therefore refer to different states but still be accurate.
[5F16] King Of The Hill
The Murderhorn clearly doesn't exist, but see here for some discussion of similar real-life mountains.
Season Ten
[5F21] The Wizard Of Evergreen Terrace
When Homer and Bart drive to the Edison's Menlo Park Laboratory in New Jersey, Homer takes the exit to New Jersey, Michigan, Oregon, and Texas... a signpost which is clearly a joke, as these four states are opposite ends of the country from each other, so this means nothing really.
[AABF01] Treehouse Of Horror IX
Maggie signals to Kang and Kodos - and the signal can be seen emanating from Louisiana. Not that THOH episodes are canon, but I guess that just means we can conclude that for that segment of that episode, Springfield was indeed in Louisiana!
[AABF03] Lisa Gets An "A"
Superintendent Chalmers notes that Springfield Elementary was moved to its current location from Missouri, brick by brick. So Springfield is not in Missouri.
Homer says, "And now for the main course... Steamed Maine Cabbages!" which implies Springfield isn't in Maine either.
[AABF06] Viva Ned Flanders
Homer and Ned visit Las Vegas, Nevada. After being thrown out, they are dumped over the state line, and start walking in the opposite direction, implying Springfield is not in Nevada.
[AABF08] Sunday, Cruddy Sunday
While giving her address on the phone, Marge says "742 Evergreen Terrace, Springfield, oh hiya Maude, come on in!"
Let's be clear here. She doesn't say "Ohio". She doesn't start saying "Ohio" and turn it into "oh, hiya". She says "oh, hiya".
[AABF09] Homer To The Max
Homer spills fondue on his console at work, causing the state of New York to begin flashing alarmingly on the big board. However, Lenny then remarks "There goes Albany!" implying that the nuclear power plant Homer just crippled wasn't the one in Springfield. So Springfield isn't necessarily in New York.
[AABF10] Marge Simpson In: "Screaming Yellow Honkers"
Marge shouts "Go back to New Jersey!" so Springfield can't be in New Jersey.
[AABF18] They Saved Lisa's Brain
The guys from KBBL deny any knowledge of a prize trip to Hawaii, implying Springfield is not in Hawaii. The trip is in fact said to be to Hartford, Connecticut, which implies Springfield isn't in Connecticut.
Dr. Hibbert remarks that he should just move back to Alabama.
Season Eleven
[BABF05] Take My Wife, Sleaze
"We have a little saying around here: 'Let Michigan handle it'."
Also, the Hell's Satans go to a bikers' jamboree in South Dakota, presumably not Springfield's state.
[BABF08] The Mansion Family
Springfield Nuclear Power Plant's cooling towers are visible from international waters, twelve miles off the coast of America.
[BABF09] Saddlesore Galactica
Lisa is outraged at Ogdenville's cheating to win the elementary school band competition at the state fair. That places Ogdenville in the same state as Springfield.
[BABF12] Pygmoelian
Moe has a liquor license for the state of Rhode Island, which he claims he means to update for "this state", implying Springfield is not in Rhode Island.
[BABF16] Kill The Alligator And Run
Springfield is not in Florida.
From the end of this episode we can conclude that OFF does not live in North Dakota or Arizona... and also that they are unwelcome in whichever state they DO live in.
[BABF19] Behind The Laughter
In the first airing of this episode, the narrator gives Springfield's location as northern Kentucky. For the second and some later airings, this changed to Southern Missouri.
However, this episode is not canon. It portrays the show not as a cartoon created by Matt Groening, but as a live-action sitcom originally written by Homer and starring his own family. None of what happens is part of the main Simpsons continuity... exactly like any Halloween Special.
Season Twelve
[BABF20] A Tale Of Two Springfields
The telephone company splits the city into 2 separate area codes, 939 and 636. 939 is the area code for Puerto Rico and 636 is located in Missouri. Interestingly enough, while Missouri does have a city named Springfield (along with an airport), Springfield does not appear to be located in 636. Rather, it's located in the 417 area code.
[CABF01] Lisa The Tree Hugger
When Lisa first climbs the giant redwood tree she is treated to a stunning view of Springfield and Shelbyville - and also the Gateway Arch in St. Louis, Missouri. This would put Springfield firmly in either Missouri or Illinois (from which the Arch is probably also visible) - except that the Statue of Liberty is also visible in the image. Which is impossible. Not only is the Statue of Liberty over five hundred miles away - far too small to visible from Missouri - the redwood tree in question would need to be about a dozen miles tall for it to even be visible due to the curvature of the Earth. Add in the fact that the Eiffel Tower is ALSO in the image, and appears to actually be NEARER than the Statue of Liberty, and what you have, alas, is nothing more than a meaningless sight gag.
[CABF04] Homer vs. Dignity
Burns remarks, "Whoah, slow down. There's a new Mexico?" which means Springfield is not in New Mexico (and is also the exact same joke as used in [1F06] Boy Scoutz 'N The Hood).
[CABF13] Simpson Safari
Homer, Lisa and Bart are grocery shopping. Bart indicates that he is "out of wine" and throws a gallon jug in the cart. In Pennsylvania, the only place to purchase wine is at state-regulated liquor stores. It is one of the few states in which alcohol cannot be sold in grocery stores. So Springfield cannot be in Pennsylvania.
[CABF17] Simpsons Tall Tales
The Simpsons are going to Delaware! So presumably Springfield is not in Delaware.
They cross the river Mississippi on the way.
Season Thirteen
[DABF03] Sweets And Sour Marge
Homer refers to the next state south of Springfield being Tennessee. Assuming Homer knows his geography, Tennessee is south of the borders of Kentucky, Missouri and Virginia.
[DABF04] Half-Decent Proposal
Homer gets a job on an oil rig in West Springfield, which is three times the size of Texas, and roughly the same shape. Texas is already huge, so this sets severe limitations on where within America's mainland Springfield will even fit.
[DABF06] The Bart Wants What It Wants
Homer promises to send Lisa to the finest school there is... in South Carolina.
[DABF09] The Old Man And The Key
Lisa says Branson, Missouri is a thousand miles away from Springfield, which, realistically, could mean anything from 500 to 1500 miles.
[DABF10] Blame It On Lisa
When asked about Springfield's location by her Brazilian pen pal, Lisa cryptically replies, "it's a bit of a mystery, yes. But if you look at the clues, you can figure it out." As best as we can tell from looking at the clues, this is untrue.
[DABF11] Weekend At Burnsie's
Medicinal marijuana is legal in Springfield's state at the beginning of this episode, placing it in Alaska, California, Colorado, Hawaii, Maine, Nevada, Oregon, or Washington. But then it gets illegalised halfway through the episode. What can we conclude from this? Pretty much nothing, to be honest...
[DABF14] The Sweetest Apu
The "Second Battle of Springfield" from the American Civil War is re-enacted in this battle. There was a real Battle of Springfield II in the Civil War, which took place in Springfield, Missouri. However, given that three sides fight in this episodes, this could conceivably be a different battle.
[DABF17] Poppa's Got A Brand New Badge
When Homer advertises his private police force, he gives the number 636-555-3472. The 636 area code is in Missouri. However, this area code is clearly given to fit in with established Simpsons continuity from [BABF20] A Tale Of Two Springfields. (A rare occurrence indeed.) Had Homer lived in the other half of Springfield, making his number 939-555-3472, then I don't think we could sensibly conclude that Springfield was in Puerto Rico...
The sign seen as Fat Tony and his goons drive into Springfield lists a city population of 30,720 and an elevation of 1,582 feet above sea level. The population is irrevelant as none of those 30,720 people actually exist, but the elevation figure restricts Springfield's location to the complicated strip of American soil which sits at precisely this elevation.
Springfield Nuclear Power Plant is on Interstate 95, which runs along the East coast of the USA from Florida all the way through Georgia, South Carolina, North Carolina, Virginia, Maryland, Delaware, Pennsylvania, New Jersey, New York, Connecticut, Rhode Island, Massachusetts and New Hampshire to Maine. Fat Tony mentions some of his Mafia buddies flew in from New Jersey, which rules out... well, to be honest, only New Jersey.
Season Fourteen
[DABF20] Bart vs. Lisa vs. 3rd Grade
There's a brief scene in which a satellite TV signal from OFF's house can clearly be seen originating in Illinois.
Sringfield's state's state bird is the pot-bellied sparrow, and its state pasta is bow tie (whatever THAT might imply).
The state flag is a Confederate flag partially immersed in water, with sun rays behind it. Also, the Capital City Goofball refers to Springfield's state as "a northern state". (This contradicts [7F01] Two Cars In Every Garage, Three Eyes On Every Fish which gives this flag.)
[EABF02] Special Edna
Skinner drives Willie's car from Springfield to Orlando and passes a sign saying Orlando, 2653 miles. The Springfield in this episode could be in Oregon, California, Idaho, Washington or possibly Montana.
[EABF15] Brake My Wife, Please
Homer takes a song-sequence walk from Springfield to Alaska. In the brief shot of America, Springfield is represented by a solitary blue star which seems to be in Missouri.
[EABF16] The Bart Of War
After seeing Marge and Lisa's smoke signal, Mr Burns remarks that "The Pawnee have returned!" suggesting that Springfield was once Pawnee territory, that is, somewhere in South Dakota, Nebraska, Iowa, Kansas or Missouri.
Nelson remarks that a field in Springfield looks "Awful! It looks like Wisconsin!" implying Springfield is not in Wisconsin.
Season Fifteen
[FABF08] The Ziff Who Came To Dinner
The (frankly awe-inspiring!) couch gag for this episode depicts Springfield on a straight line between Florida (bottom right) and Canada's Lake Winnipeg (the small blue body of water on the top edge of the cloud). That places Springfield in either Illinois or Wisconsin. Of course, we have to bear in mind that couch gags aren't canon - Kang and Kodos don't exist, nor is the entire Simpsons universe contained in Homer's brain...
Season Sixteen
[FABF16] Midnight Rx
Homer says his family's backyard celebration is "just like Hawaii".
[GABF04] There's Something About Marrying
Springfield can apparently be reached via Route 202.
Gay marriage is made legal in Springfield in this episode, but as with the marijuana episode, Weekend At Burnsie's (above), we can't conclude anything from this. Do we take states where gay marriage is legal? Where it is illegal? Where it was illegal until recently? The real fact of the matter is that the writers of that episode did not base what they wrote on a real-life state's legislative moves. So unfortunately we can't take anything from this.
Season Seventeen
[GABF18] Bonfire Of The Manatees
Marge encounters Florida manatees in this episode. "Florida manatee" is not a species of manatee but refers to the location where they are found. In other words, Marge must have driven to the Florida coast for this episode. However, we don't know how far she has driven; she may have crossed state lines.
[HABF02] The Italian Bob
Chief Wiggum, Lou and Eddie burst into an old haunt of Sideshow Bob's, where a Penn State pennant is prominently displayed on the wall. This could imply that Springfield is in Pennsylvania, but on the other hand it could just mean that the room's current occupants studied there.
[HABF10] Kiss Kiss Bang Bangalore
When Homer is told he is going to India to train the replacement workers for the nuclear power plant he yells "Woo Hoo! The Simpsons are going to India! Home of the Indianapolis 300...," confusing his destination with Indiana. So Springfield cannot be in Indiana.
Season Eighteen
[HABF21] G.I. D'oh
Dolph, Jimbo and Kearney are referred to as the dumbest teenagers in the dumbest town in the dumbest state. One source lists Arizona as the dumbest state during this episode's production.
[JABF04] Little Big Girl
Springfield is not in Colorado, as Homer orders "Rocky Mountain Chew" from Colorado.
Springfield is not in Utah, as that's where Bart and Darcy have to travel.
Bart's imagination seems to know a lot about Utah's geographic features for a ten-year-old "underachiever". Perhaps this, along with the apparent relatively short drive places Springfield near Utah or at least somewhere in the Western US?
The Simpsons Movie
The Simpsons Movie has Ned Flanders showing Bart the four states which border Springfield: Ohio, Nevada, Maine and Kentucky. It would be difficult to pick four states further apart from one another, which makes the entire thing an obvious joke. On the other hand, since Ned is not a particularly unreliable narrator, it is vaguely conceivable that this is actually TRUE, which, combined with the evidence for [8F01] Mr. Lisa Goes To Washington and [5F21] The Wizard Of Evergreen Terrace (both listed above), leads to the unavoidable conclusion that the layout of US states in the Simpsons universe is different from our own.
The new Grand Canyon - to be opened on the site of Springfield - is announced to be "east of Shelbyville and south of Capital City", which gives us a little information about the geography of Springfield's state.
The Fox Network ran a competition among various real-life Springfields to see which one would get to host the official premiere of The Simpsons Movie. The winner was Springfield, Vermont, but contrary to popular belief, it was NOT named the real Springfield.
Season Nineteen
[KABF04] E Pluribus Wiggum
Springfield's 2008 Presidential Primary is moved to be a week ahead of New Hampshire's (January 8, 2008), becoming the first in the 2008 United States Presidential Election season. Logically, Springfield cannot be in New Hampshire. When the news breaks, a reporter asks "Which Springfield?" to which the response is "The one the Simpsons live in!"
Multiple references to "the Springfield Primary" suggest that Springfield may actually be in the state of "Springfield". This would go a long way to explaining why Springfield is so frequently referred to without any state being named: Springfield is in Springfield in the same way that the city of New York is in the state of New York and to mention both would be superfluous. It would also explain why the Simpsons' address is always given as "742 Evergreen Terrace, Springfield, USA" - Springfield is both the city and the state. Note that the fact that Capital City is a separate settlement does not contradict this: the capital of the state of New York is not New York, but Albany.
Season Twenty
[LABF05] Wedding For Disaster
During the couch gag, Comic Book Guy eats a four-course meal based on the Simpsons - the bill comes to $45.84 plus $3.78 tax, or 8.25%. Couch gags are not canon, however.
[LABF08] Father Knows Worst
Noah (correctly) lists the following state capitals, in alphabetical order: Albany, Annapolis, Atlanta, Augusta, Austin, Baton Rouge, Bismarck, Boise, Boston, Capital City and Carson City. These are the capitals of New York, Maryland, Georgia, Maine, Texas, Louisiana, North Dakota, Idaho, Massachusetts, Springfield's state and Nevada respectively. Springfield cannot be in New York, Maryland, Georgia, Maine, Texas, Louisiana, North Dakota, Idaho, Massachusetts or Nevada.
[LABF12] Coming To Homerica
After Ogdenvillians of Norweigan descent migrate to Springfield, Milhouse remarks "Minnesota Vikings apparel? This is Tennessee Titans country!". This implies that Springfield is near Nashville, Tennessee, while neighbouring city Ogdenville is near Minneapolis, Minnesota.

[Ratty Randnums]

Well, since they've shown the town as next to the ocean and next to a giant canyon, AND within a fairly short distance of Canada, I don't think it could geographically exist anywhere.

Many people in the state of Kentucky believe it was originally based on that state's Springfield though. Which is right next to Shelbyville (like in the show) and Simpsonville. Plus Jebediah Springfield can be seen as an obvious reference to state hero Daniel Boone. (Who has many statues resembling the one Bart decapitated.)

[gavdaman88]

There's a town in Mass. USA called Springfield, and near it is a town called Shelburn falls.... suspicious!

[psychokind]

amazing, the amount of information, that is!

[Jason Tandro]

Ratty Randnums wrote:

Well, since they've shown the town as next to the ocean and next to a giant canyon, AND within a fairly short distance of Canada, I don't think it could geographically exist anywhere.

Basically it's supposed to be Anytown, USA. But it could be in Washington, Oregon or California and still fall in that subset. I guessed Washington, but then switched to California.

[chicken]

so do we know where it is or not?

[Freedan]

Don't forget the movie. Flanders points out that the 4 states that border Springfield are Nevada, Ohio, Kentucky and Maine (all visible from Springfield).

Two of those states are on opposite sides of the country. Hell, they're all pretty far apart. And if memory serves, there's about 35 states that have a "Springfield" in it somewhere.

Springfield is a mystery that shall never be solved.

Edit: Also, Jason, you have way too much spare time to go finding all of that.

[Jason Tandro]

Oh this isn't MY research. I'm just posting it.