First employed by political analyst Kevin Phillips in his 1969 book "The Emerging Republican Majority", the term "Sun Belt" became synonymous with the southern third of the nation in the early 1970s. In this period, economic and political prominence shifted from the Midwest and Northeast to the South and West. Factors such as the warmer climate, the migration of workers from Mexico , and a boom in the agriculture industry allowed the southern third of the United States to grow economically. The climate spurred not only agricultural growth, but also the migration of many retirees to retirement communities in the region, especially in Florida and Arizona.