Miami-Dade County remains the most populous county in Florida, but new U.S. Census estimates show its growth is beginning to slow, and in the most recent year, reverse.
The county’s population reached about 2.8 million in 2025, reflecting a 3.7 percent increase since the 2020 census. But between 2024 and 2025, Miami-Dade lost more than 10,000 residents, placing it among the largest numeric declines in the country.
The shift mirrors a broader national trend in which large urban counties are seeing slower growth as migration patterns change.
Census data shows that domestic out-migration – residents moving to other parts of Florida or the country – continues to impact major metropolitan areas like Miami. At the same time, lower international migration have reduced the number of new residents that usually offset those losses.
Across Florida, population growth remains strong overall but is increasingly concentrated in smaller and mid-sized regions such as Ocala and Lakeland, which are attracting new residents with lower costs of living.
For Miami-Dade, the data suggests not a population collapse, but a recalibration.
Miami-Dade County ranked third in the nation for population decline between July 2024 and July 2025, losing more than 10,000 residents, according to U.S. Census Bureau estimates.
US Census
The county is still growing compared to 2020, but at a slower and less predictable pace. For communities like Key Biscayne, the trend reflects a balancing act between continued demand for South Florida living and the rising costs that may be pushing some residents to look elsewhere.