Bethlehem is a city in Lehigh and Northampton counties in the Lehigh Valley region of the eastern portion of the U.S. state of Pennsylvania. 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. Of this, 55,639 were in Northampton County, and 19,343 were in Lehigh County.
Bethlehem lies in the center of the Lehigh Valley, a region of 731 square miles that is home to more than 800,000 people. Together with Allentown and Easton, the Valley embraces the Allentown-Bethlehem-Easton, PA-NJ metropolitan area, including Lehigh, Northampton, and Carbon counties within Pennsylvania, and Warren County in the adjacent state of New Jersey. Smaller than Allentown but larger than Easton, Bethlehem is the Lehigh Valley's second most populous city. In turn, this metropolitan area comprises Pennsylvania's third-largest metropolitan area and the state's largest and most populous contribution to the greater New York City metropolitan area.
There are four general sections of the city: central Bethlehem, the south side, the east side, and the west side.