Immigration was a key factor in the growth of the largest urban counties in the United States last year, as revealed by the U.S. Census Bureau’s latest population estimates. Significant metropolitan areas such as Houston, Miami, and Phoenix saw remarkable growth largely due to the influx of individuals from outside the country. Without international migration, counties like Harris in Texas, Miami-Dade in Florida, and Maricopa in Arizona might not have experienced any population increase, as domestic migration saw more residents leaving than moving in. Particularly, Miami-Dade County would have witnessed a population decline if it wasn’t for immigration, since the higher birth rates were insufficient to compensate for the exodus of local residents.
In 2024, immigration propelled the U.S. population to grow at its highest rate in over two decades, pushing the national population past the 340 million mark. Notably, the Census Bureau’s adjusted methodology now accounts for more immigrants, including those entering the U.S. for humanitarian and temporary reasons. “Historically, a natural increase, with births surpassing deaths, has driven U.S. population growth. However, as this margin shrinks, immigration has become the primary source of growth recently,” commented Kenneth Johnson, a senior demographer.
A divide persists between choices of domestic and international migrants, as seen in the 2024 estimates. While immigrants gravitated towards the urban cores of metropolitan areas, domestic movers favored the farther suburbs. Miami-Dade and Harris counties emerged as the top destinations for international newcomers, followed closely by Los Angeles and Cook County in Illinois. Meanwhile, Montgomery County in Texas, Pinal County in Arizona, and Pasco County in Florida, among others, were preferred by domestic movers.
The New York metropolitan area exemplified a remarkable recovery post the COVID-19 pandemic’s population slump. This region, the largest in the U.S. with a nearly 19.9 million population, welcomed more new residents than any other area last year. Although 147,000 residents moved out, about 288,000 immigrants arrived, many of whom came on bus services from Texas. Similarly, San Francisco and Washington, D.C. have experienced population rebounds thanks to international migration after facing declines during the pandemic’s peak. New York also led the country in natural population growth, seeing a significant surplus of births over deaths.
South Florida advanced in rank to claim the position of the sixth most populous metropolitan area in the nation, surpassing metro Washington and metro Atlanta. Meanwhile, in North Carolina, metropolitan Charlotte overtook metro Baltimore for the 21st spot. Within counties, Tarrant County in Texas, home to Fort Worth, ascended to become the 15th most populous county, surpassing San Bernardino County in Southern California.
Despite two-thirds of the 3,144 U.S. counties experiencing growth last year, many still faced a natural decrease due to deaths surpassing births. This phenomenon underscores the critical role of immigration in driving overall population growth since the pandemic’s onset. Kenneth Johnson noted that the natural growth reported last year was less than half the average annual increase that the U.S. enjoyed during the five years leading up to the pandemic, highlighting an unprecedented period of natural decrease.
