While Hillsborough added 230,000 residents over ten years, Pinellas shrank.
The University of Florida released its latest estimates for changes to Florida's population between 2000 and 2010, and two adjacent Gulf Coast counties find themselves on opposite ends of the growth spectrum.
According to the university, Hillsborough County added 230,278 residents between 2000 and 2010, the third-largest numerical increase among all 67 counties in Florida.
Over that same time period, Pinellas County lost nearly 5,000 residents, and was one of just two Florida counties to see its population decline over the decade.
The data show that Tampa's growth is continuing to outpace that of St. Petersburg, while Pinellas' high population density is holding future growth back.
Overall, the state added roughly 2.8 million residents between 2000 and 2010, the university estimates. That's an increase of 17.6%, to 18.8 million residents.
Florida's population growth was the third-largest numerical increase in the country, and the eighth largest by percentage.