Northampton County is a county in the Commonwealth of Pennsylvania, United States. As of the 2020 census, the population was 312,951. Its county seat is Easton. The county was formed in 1752 from parts of Bucks County. Its namesake was the county of Northamptonshire in England, and the county seat of Easton was named for Easton Neston, a country house in Northamptonshire.
Northampton County and Lehigh County to its west combine to form the eastern Pennsylvania region known as the Lehigh Valley; Lehigh County, with a population of 374,557 as of the 2020 U.S. census, is the more highly populated of the two counties. Both counties are part of the Philadelphia media market, the fifth-largest in the nation.
Northampton County has historically been a national leader in heavy manufacturing, especially of cement, steel, and other industrial products. Atlas Portland Cement Company, the world's largest cement manufacturer from 1895 until 1982, was based in Northampton in the county. Bethlehem Steel, the world's second-largest manufacturer of steel for most of the 20th century, was based in Bethlehem, the county's most populous city, prior to its dissolution in 2003.
Northampton County borders Carbon County and the Poconos to its north, Lehigh County to its west, Bucks County to its south, and the Delaware River and New Jersey to its east. The Lehigh River, a tributary of the Delaware River, flows through the county.
Geography
thumb|The [[Easton–Phillipsburg Toll Bridge, which connects Easton in Northampton County with Phillipsburg in northwestern New Jersey in the Lehigh Valley, in October 2009]]
According to the U.S. Census Bureau, the county has a total area of , of which is land and (2.0%) is water. The climate is humid continental (mostly Dfa with a little Dfb in higher northern areas) and the hardiness zone is 7a except in the northern tier where it is 6b. Average monthly temperatures in downtown Bethlehem average from 29.1 °F in January to 74.1 °F in July, while in Wind Gap, they average from 27.0 °F in January to 71.7 °F in July. Both the Lehigh and Delaware rivers flow through the county. Kittatinny Ridge is to its north. South Mountain is to its south. Paxinosa Mountains are to its east.
Adjacent counties
- Monroe County (north)
- Warren County, New Jersey (east)
- Bucks County (south)
- Lehigh County (west)
- Carbon County (northwest)
National protected areas
- Delaware Water Gap National Recreation Area (part)
- Middle Delaware National Scenic River (part)