Back to list April 30, 2019 Cumberland County Still the Fastest Growing in Pennsylvania The Old Courthouse in downtown Carlisle According to this article from Central Penn Business Journal Cumberland County remains the fastest-growing county in Pennsylvania. “The Pennsylvania State Data Center, which analyzes U.S. Census Bureau data, said Thursday that Cumberland County saw its population rise by 6.8 percent between 2010 and 2018.” “The data center said the southcentral and southeastern counties continue to be the bright spots in Pennsylvania for population growth as the northern and western parts of an aging commonwealth decline.”