As one who has lived in 11 states, I have yet to find a state that is all "one state".
Idaho is 3 states: Northern is basically the eastern part of Washington State, Eastern is basically the northern region of Utah, only the Boise area can rightfully claim a culture and lifestyle of it's own.
Utah is 3 states: You have northern Utah, Southern Utah, and The Desert.
Florida: The Gulf coast, the Atlantic Coast, the Panhandle, the Keys and Miami/Ft. Lauderdale.
"The Carolinas": The rest of the country calls them North and South Carolina, but for the locals its either "The Carolinas" or simply "Carolina". There really are two, but the division is between the eastern and western ends of both states rather than the state line.
Virginia: The coast, the City (Richmond area) and "The Mountains", each have a unique flavor.
Oklahoma: There is "The City" and "The Desert", that's about it.
Ohio: Up north is Midwestern living through and through, down south, by listening to them talk, you'd think your were "down south". It's more Kentucky than midwest.
Georgia: In Georgia you are either in the city (trying to convince the world that there really are cities in Georgia), or your in the country (and you don't care whether the rest of the world thinks you have paved roads or not). If you're in the city, you make fun of the "Rednecks" in the country, if you're in the Country, you proudly accept the label "Redneck" and make fun of "Those City People". That, or you're doing everything you can to get out of the country, shake your "Redneck" roots and become a "City People".
Wisconsin: There are basically 4 Wisconsins. Milwaukee area, Green Bay Area, Western Wisconsin and Northern Wisconsin. Nortern Wisconsin requires a passport, language training and "Fishing Shanty", unless you're just passing through. These can only be seperated from "Da Yoopers" by the most discerning ear (or the local who just shot you for calling her "A Yooper". ;~D
California: There are arguments to how many Californias there are. As you point out, there is "Southern" and "Northern" California. Even more argument exist over exactly where the line between them would be. From my experience, I see 5 Californias. There is the classic "Southern" California, famed in Song, Story and Surfer. Central California is the California that is still part of The West. Ranches, Vinyards, Rodeos (even if they do pronounce it wrong)..etc. Then there is "The Bay Area", San Francisco and all points connected. Northern Californias Redwoods, small towns and Sacremento (capital) would never be mistaken for any other part. The 5th part would be "The Desert". These are mostly in Southern California, and are definitely "Sunny", but who could possibly mistake Barstow with, well anywhere else in the world (except maybe Parhump, NV. ;~D
Sorry that ran so long, but those are the states and their differences (from my own experiences). I completely expect to catch crap from people who disagree. I hope I didn't hijack your article!!! If you think that might happen, go ahead and delete it and I'll post it as a seperate article. For me though, I think it works as a decent followup to yours.
From what I see here, if we're going to split states up by cultural and geographic differences, we'd end up with well over 200 states!!! ;~D