There is a huge variety of different Springfield accents: accents of the English language spoken by presumed native residents of the town of Springfield. Studying the local or regional accent(s) of the town's citizens is one hypothetical way to identify the location of Springfield and Springfield's state within the United States. Most Springfield children and many adults born and raised in Springfield speak with a regionally-nonspecific General American accent (for example, Homer Simpson); General American is best associated with the Northern and Western United States. Some middle-aged Springfielders occasionally show "th"-stopping, a usual marker of the working class, including Homer as well as Police Chief Clancy Wiggum (such as when "this" sounds almost like "diss").
A considerable number of the middle-aged generation of Springfield citizens have the accent of the greater New York metropolitan area. Marge Simpson and Barney Gumble both exhibit rhotic New York metropolitan accents (as spoken, for example, in Long Island or North Jersey), while Carl Carlson and Lenny Leonard, as well as Moe Szyslak (who is not a Springfield native, but who moved there as a young child), all exhibit the authentically non-rhotic (or "r"-dropping), working-class accent of New York City itself (as spoken, for example, in Brooklyn).
Others living most if not all their lives in Springfield show a recognizable accent local to the Southern United States. Ned Flanders shows traces of a Southern accent, though this is perhaps not a regional marker for him as much as a cultural marker of his self-identification with Southern Baptism or the Evangelical Christianity associated culturally with the South and its "Bible Belt" region (however, his accent in his childhood flashbacks still seems to be lightly Southern, while being different from his probably non-Evangelical parents, who were beatniks). Members of Springfield's Spuckler family show deep Southern accents, complete with lexical Southern usages like "y'all" and even double modals (such as when Cletus says "You might could wear these to your job interview."). The apparently Southern-accented Rich Texan is confirmed to be from neither Springfield nor Texas.
Mayor Joe Quimby has a non-rhotic Eastern New England (Boston) accent, with exaggerated intonations seeming to imitate Ted or John F. Kennedy.
One possibility to explain Springfield's diversity of accents is that different socioeconomic groups in the town have different accents, or that the town is a linguistic melting pot, perhaps because it is located midway between a variety of dialectal regions. Ned Flanders's comment that Springfield borders Ohio, Nevada, Maine, and Kentucky, though geographically impossible, would lend credit to this theory. The best explanation might be that Springfield has had a lot of recent immigration of speakers from various areas of the country.