Lehigh County (; Pennsylvania Dutch: Lechaa Kaundi) is a county in the Commonwealth of Pennsylvania. As of the 2020 census, the county's population was 374,557.Lehigh County at U.S. Census Quick Facts Its county seat is Allentown, the state's third-largest city after Philadelphia and Pittsburgh.
lehigh county (; pennsylvania dutch lechaa kaundi) is a county in the commonwealth of pennsylvania as of the 2020 census the county's population was 374557lehigh county at us census quick facts its county seat is allentown the state's third-largest city after philadelphia and pittsburgh