The Sun Belt stretches across the southern third of the United States, running from Virginia and Florida in the Southeast all the way west through Nevada and southern California. It encompasses 15 states along with portions of a few others, all sitting below roughly the 36°30′ north latitude line. Together, the South and West regions that make up the bulk of the Sun Belt now account for over 60% of the U.S. population.
How the Sun Belt Is Defined
Political analyst Kevin Phillips coined the term “Sun Belt” in 1969, using it to describe a broad swath of southern and western states he saw as politically and economically ascendant. The concept merges two traditional American regions, the South and the West, into a single identity tied to warm climate, population growth, and economic opportunity.
Geographically, the most widely used boundary is the 36°30′ north latitude line, the same parallel that once marked the Missouri Compromise boundary. The Kinder Institute for Urban Research at Rice University defines the Sun Belt as the states falling south of this line. In practice, though, the borders are fuzzy. Some definitions pull in states like Virginia and North Carolina that straddle the line, while others stick more tightly to the Deep South and Desert Southwest.
States Typically Included
Most definitions list 15 core Sun Belt states. They break into two broad clusters:
- Southeast: Virginia, North Carolina, South Carolina, Georgia, Florida, Alabama, Mississippi, Louisiana, Tennessee, and Arkansas
- Southwest and West: Texas, New Mexico, Arizona, Nevada, and southern California (with California sometimes counted in full)
Some broader definitions also pull in Oklahoma, Utah, and Hawaii. The exact list depends on who is drawing the map and whether they emphasize latitude, climate, or cultural and economic characteristics. You will find slightly different state counts in political science, real estate, and demographic research, but the 15-state core remains consistent across most sources.
The Southeast vs. the Southwest
Although they share a label, the two halves of the Sun Belt developed very differently. The Southeast has deep historical roots tied to agriculture, the plantation economy, and the civil rights movement. The phrase “New South” emerged in the twentieth century to describe the region’s shift toward manufacturing, finance, and technology. Cities like Atlanta, Charlotte, and Raleigh became economic engines that drew millions of new residents from northern states.
The Southwest, by contrast, remained sparsely populated well into the 1900s. Remote location and a harsh desert climate with triple-digit summer temperatures kept settlement slow until air conditioning, federal water projects, and military installations transformed the landscape. Phoenix, Las Vegas, and Albuquerque essentially became modern cities in a single generation, fueled by defense spending during and after World War II and later by retirees and tech companies seeking lower costs and open land.
Population Growth That Reshaped the Country
The Sun Belt label stuck because the migration patterns were dramatic. Between 1970 and 2020, the total U.S. population grew by 63%, averaging about 10.3% per decade. Sun Belt states grew by 119% over the same period, nearly double the national rate, averaging 17% per decade. For comparison, the Rust Belt states of the industrial Midwest grew by just 19% across those five decades, or roughly 3.5% per decade.
That gap has only widened in recent years. As of 2025, the South alone holds about 133.8 million people (39.2% of the national total), while the West accounts for another 80.1 million (23.4%). Combined, those two census regions represent nearly two-thirds of all Americans. Texas, Florida, Georgia, Arizona, and North Carolina have consistently ranked among the top states for net domestic migration, pulling residents from the Northeast and Midwest with lower housing costs, no state income tax in some cases, and expanding job markets.
Why the Boundaries Still Shift
The Sun Belt is as much an economic and cultural concept as a geographic one. When Phillips introduced the term, it was a political shorthand for conservative-leaning, growth-oriented states challenging the dominance of the industrial North. Today it carries connotations of suburban sprawl, tech corridors, retirement communities, and rapid diversification.
That means the boundaries flex depending on context. A demographer might include any fast-growing metro below the 37th parallel. A political scientist might focus on the electoral shifts Phillips originally described. A real estate analyst might define it by housing permit data, which would spotlight metros like Austin, Nashville, and Phoenix while leaving slower-growing Sun Belt cities off the list entirely. The 15-state core gives you a reliable starting framework, but the Sun Belt has always been more of a trend line than a fixed border on a map.