In March of 2020, the U. S. Census Bureau released the estimated 2019 population for all counties in Pennsylvania, along with data describing the people who were moving in and out of each county. This data set (which has been maintained since 2010) shows that over the last ten years, Chester County’s population estimate grew by 25,064 (or 5.01%), which is the 5th largest county percent increase in the state, and the 4th largest increase in total numbers.