I was speaking more specifically of the comics, where they avoided directly placing any of DC's fictional cities in a particular state. Any guesses as to where "Central City" and "Coast City" were supposed to be?
Coast City was explicitly stated as being in California in Green Lantern's comics on various occasions. A "New Adventures of Superboy" story features the Kents visiting relatives "clear across the country" in Coast City for a weekend (where they meet a teenage Hal Jordan);the references in the story make clear that Smallville (in that story) is near Metropolis (the Kents take off from a Metropolis airport, and they mentioned Smallville being an east coast town repeatedly).
Central City is somewhere in the midwest; in the 70's, think it was placed in Ohio, while post-Crisis, they moved it to Missouri (as a "twin city" to Keystone City, which post-Crisis is in Kansas... which I always thought was stupid--- "Keystone City" was supposed to be more of a Pennsylvania-type city... the "keystone state" and all?! Dont' see why the two cities couldn't straddle the Ohio-Pennsylvania border instead... and it'd at least leave their original individual identities mostly intact, instead of diminishing them both by making them some lame Kansas City-knockoffs...).