Bethlehem is a city in Lehigh and Northampton Counties in the Lehigh Valley region of eastern Pennsylvania, in the United States. As of the 2010 census, the city had a total population of 74,982, making it the seventh largest city in Pennsylvania, after Philadelphia, Pittsburgh, Allentown, Erie, Reading, and Scranton.
Bethlehem lies in the center of the Lehigh Valley, a region of 731 square miles (1,893 km²) that is home to more than 800,000 people. The Valley embraces a trio of cities (Bethlehem, Allentown and Easton) within two counties (Lehigh and Northampton), making it Pennsylvania's third-largest metropolitan area. Smaller than Allentown but larger than Easton, Bethlehem is the Lehigh Valley's second most populous city.
There are three general sections of the city, North Bethlehem, South Bethlehem and West Bethlehem. Each of these sections blossomed at different times in the city's development and each contains areas recognized under the National Register of Historic Places. Zip codes that use the address Bethlehem totaled 116,000 in population in the year 2000. These zip codes include Bethlehem Township.