Living on the somewhat insular conceptual isle of Pink Manhattan (yes, it's as much a conceptual place as "Hollywood", although I really am in NYC, like there's an actual place called Hollywood, CA), I only know of a Borscht Belt and a Bible Belt; till now, I'd never heard of a Sun Belt (aka 'Sunbelt') or any of the other belts listed on Wikipedia (Jell-O Belt (Mormon Corridor), Unchurched Belt, a literally racist Black Belt (although it is stated that the original use of the term was related to the soil in the region) and more at this link: List of belt regions of the United States).
"The Sun Belt is a region of the United States generally considered to stretch across the South and Southwest (the geographic southern United States). Another rough boundary of the region is the area south of the 36th parallel, north latitude. It is the largest region which the U.S government does not recognize officially (in its postal regions and census). The main defining feature of the Sun Belt is its warm-temperate climate with extended summers and brief, relatively mild winters; Florida, the Gulf Coast, and southern Texas, however, have a true subtropical climate.
"The Belt has seen substantial population growth in recent decades (1960s to recent) fueled by milder winters; a surge in retiring baby boomers who migrate domestically; and the influx of immigrants, both legal and illegal. This population boom has been less substantial in Louisiana, Mississippi, and Alabama compared with their western and eastern neighbor states. Also, over the past several decades, air conditioning has made it easier for people to deal with the heat in portions of the region during the summertime. Water shortages are becoming a common problem in the region.
(...) "Author and political analyst Kevin Phillips claims to have coined the term "to describe the oil, military, aerospace and retirement country stretching from Florida to California" in his 1969 book The Emerging Republican Majority.
(...) "Since 1970, the Belt states have gained 25 electoral votes. Since Lyndon B. Johnson's election in 1964, every elected United States President, with the exception of Barack Obama from Illinois, has been from the Sun Belt. (Gerald Ford, who was from Michigan, became president following Richard Nixon's resignation, but was not elected as president, and lost to Georgia's Jimmy Carter in the 1976 election.)" Read more: Sun Belt From Wikipedia, the free encyclopedia