By Cathy Le and George M. Hayward
Fifty, or 1.6%, of the United States’ 3,144 counties had at least one million people on July 1, 2024, more than double the number (23) in 1970.
According to the U.S. Census Bureau’s county-level population estimates, which date back to 1970, only 54 counties have ever crossed the one-million-person mark. By 2024, four had slipped below one million, bringing the total to 50.
