Jefferson County Flag

Jefferson County

State:
Pennsylvania
County Seat:
Brookville

Jefferson County's 2026 population is estimated at 42,851, reflecting a -0.6% growth rate over the past year (World Population Review estimate based on U.S. Census Bureau data). Jefferson County is the 49th largest county in Pennsylvania. The 2010 population was 45,163 and has grown -5.12% since 2010.

42,851
Total Population
66
Population Density (mi²)
49
Population Rank (State)
-258 -0.6%
Annual Population Growth

Jefferson County Population

Demographics

Economics and Income Statistics