Sun Belt (or Sunbelt)

Texas is part of the “sun belt” states of the South. The term has existed from at least the 1920s, but was popularized in the late 1960s when federal government programs specifically used the term.
 
It is claimed on some websites that Texan Sam Rayburn (Speaker of the House of Representatives) coined “sun belt” when legislation was proposed for “Route 66,” but the “sun belt” term had existed earlier. Also, no documentary evidence shows his “sun belt” use at that time.
 
 
(Oxford English Dictionary)
Sunbelt U.S. (also as two words) [BELT n.1 5a], a zone consisting of the most southerly states of the U.S., extending from California in the west to the Carolinas in the east
1969 K. P. PHILLIPS Emerging Republican Majority v. 438 Chart 134 illustrates how the electoral votes of the *Sun Belt will have almost tripled in the half-century between 1920 and 1970.
 
2 February 1920, Los Angeles Times, pg. II8 (heading):
Nine ball teams to begin training in Sun Belt.
 
11 November 1923, Boston Globe, pg. 25:
Each round [of golf] may be the last for those who have no plans ahead to follow the sunbelt.
 
7 December 1947, New York Times, pg. 323: (heading):
A calendar of fiestas, fairs and Mardi Gras in the Sunbelt.
   
29 May 1960, Pasadena (CA) Independent Star-News, Parade magazine, pg. 6:
One of the best, they suggest, is to visit the sun-belt states during summer. After April, for example, the hotel rates in Miami Beach plummet sharply. In Arizona, another sunshine state, the hotel rates drop 30 percent.