Air conditioning helped move America's centre of gravity south
Seven of the ten largest cities in the United States now lie in the warm southern band known as the Sun Belt, from Los Angeles and Phoenix to Houston and San Antonio. That shift was not inevitable. Among its enablers was a humble machine: air conditioning made the region's summers bearable enough for millions of newcomers and their factories.
The Sun Belt stretches across the American Southeast and Southwest, roughly the land south of latitude 36°30′ north. It spans deserts in Arizona and Nevada, a Mediterranean climate in California, humid subtropics from Texas to the Carolinas and true tropics in South Florida. The phrase itself was coined by the analyst Kevin Phillips in a 1969 book and caught on in the early 1970s, just as economic weight began tilting away from the Midwest and Northeast.
Many forces drove the migration after the Second World War. Warm weather drew retirees, especially to Florida and Arizona. Aerospace, defence and oil companies were attracted by nearby military bases and by weaker labour unions in a region that had industrialised relatively late. Farming boomed with the climate, and tourism thrived because recreation there is rarely limited to one season. Because so much building is recent, homes tend to be modern and open in design. Later, technology firms became major growth engines in California, Texas and Florida.
The pull has persisted, with pauses. The 2008–2009 recession hit the region hard and briefly slowed movement from the colder north, but migration picked up again by 2015. In 2005 the Census Bureau projected that about 88% of national population growth between 2000 and 2030 would happen in the Sun Belt, with California, Texas and Florida each gaining more than 12 million people. Since the pandemic, 86% of the fifty zip codes with the biggest influx of new residents have been in Texas, Florida and Arizona.
Growth brings strain, above all on water. California communities are planning desalination plants, and Texas, Georgia and Florida face worsening shortages driven by expanding populations and heavy per-person use. The region also hosts remarkable nature, with the largest range of distinct ecosystems in the country, from desert to rainforest.
Source: Sun Belt
