"Springfield was named after Springfield, Oregon. The only reason is that when I was a kid, the TV show Father Knows Best took place in the town of Springfield, and I was thrilled because I imagined that it was the town next to Portland, my hometown. When I grew up, I realized it was just a fictitious name. I also figured out that Springfield was one of the most common names for a city in the U.S. In anticipation of the success of the show, I thought, 'This will be cool; everyone will think it’s their Springfield.' And they do."

1. Oregon isn't easy driving distance to both Ogdenville and North Haverbrook.
   
   
   
   
   
   In the Monorail episode, Lyle Lanley discusses building monorails in both Ogdenville and North Haverbrook. (Also Brockway, but that one doesn't have the future mentions like the other two.) In dozens of episodes since, Springfield has been shown in reasonably close proximity to Ogdenville and North Haverbrook. If Lanley's map is accurate (and something about him just makes me want to trust him), Springfield can't really be in Oregon because it would take too long to get to both of the other cities from there.
   
   
2. Lisa clearly isn't pointing to Oregon when she points on the map.
   
   
   
   
   
   In the episode where Apu becomes an American citizen (after, of course, a bear invades Springfield), Lisa points to Springfield on a map. The gag is that Bart's head is blocking her... but even in the obscured view, it's clear that she's not pointing anywhere near Oregon or the west coast. It's also clear that the American flag has 13 stripes for good luck.
   
   
3. On the way to Thomas Edison's house, Homer isn't leaving Oregon.
   
   
   
   
   
   When Homer and Bart drive to Thomas Edison's house in New Jersey, they take an interstate exit that says "Exit to New Jersey, Michigan, Oregon and Texas." Yes, it's clearly a joke -- but it stands to reason the Simpsons couldn't be leaving Oregon and also exit to Oregon. It's not the nexus of the universe.
   
   
4. West Springfield needs room to be three times the size of Texas.
   
   
   
   
   
   If Springfield was in Oregon, West Springfield would extend well into the Pacific Ocean.
   
   
5. In the X-Files episode, Mulder says Springfield is in the "nation's heartland."
   
   
   
   
   
   Oregon certainly doesn't qualify as the nation's heartland. It's more like the nation's left tricep.
   
   
6. Marge pumps her own gas (in a Chanel suit).
   
   
   
   
   
   This one was sent to me by @kubrick97 on Twitter and it's perfect. Oregon is one of two states where people aren't allowed to pump their own gas. (New Jersey is the other.) In the episode where Marge joins the country club and wears various altered versions of her Chanel suit, she pumps her own gas AND teaches her old high school rival how to pump gas. Not possible in Oregon.
   
   
7. The Simpsons have been banned from Oregon.
   
   
   
   
   
   This one was sent to me by @ben_etc on Twitter. When the Simpsons are going over all the states where they're not allowed, Oregon has an "X" in it. (Of course, almost all of them do, but that's not the point. Oregon is out.)
   
   
8. Walt Whitman isn't buried in Oregon.
   
   
   
   
   
   Homer kicks Walt Whitman's grave (believe it's his mother's). Walt Whitman is actually buried in New Jersey. Leaves of grass, my ass.
   
   
9. Milhouse says Springfield is "Tennessee Titans country."
   
   
   
   
   
   When the immigrants from Ogdenville come to Springfield the kids are wearing Minnesota Vikings clothes and Milhouse adamantly expresses that it's Tennessee Titans country. I would never dare disagree with Milhouse. And as far as I know, Oregon is not considered a Tennessee Titans hotbed. (I mean... the Titans don't switch their uniforms every week using a huge palette of unbearably hideous fluorescent colors and tread patterns. How can people from Oregon possibly get behind them?)
   
   
10. When Lenny and Carl are Lewis and Clark and make it to Oregon, they name the place Eugene with no mention of Springfield.
    
    
    
    
    
    In one of the historical event episodes, Lenny and Carl (as Lewis and Clark) make it all the way west and name the place "Eugene, Oregon." Which is right next to Springfield. You'd think guys as sharp as Lenny and Carl would mention that, even in this fictional historical retelling.
    
    
11. There's no Mt. Carlmore in Oregon.
    
    
    
    
    
    Other geographical features are also missing, like a "SPRINGFIELD" Hollywood sign, a Jewish walk of fame and a box factory. But this one just stands out the most.