Lehigh County was formed on March 6, 1812 from Northampton County. Its county seat is Allentown. Lehigh County is named after the Lehigh River, which runs through the county’s two largest cities, Allentown and Bethlehem. The eastern half of Bethlehem is located in Northampton County. Lehigh County is bounded on the north-west by the Kittatinney or Blue mountains, separating it from Schuylkill and Carbon counties, north-west by Northampton, south-east by Bucks, and south-west by Montgomery and Berks counties. The county is picturesque, formed by limestone and clay slate with several creeks running through the landscape. To read about the history of the townships and boroughs that make up Lehigh County, please click on the links below.