Easton is the easternmost city in the Lehigh Valley, a region of 731 square miles (1,893 km2) that is home to more than 800,000 people. Together with Allentown and Bethlehem, the Valley embraces the Allentown-Bethlehem-Easton metropolitan area, including Lehigh, Northampton, and Carbon counties within Pennsylvania, and Warren County in the adjacent state of New Jersey. Easton is the smallest of the three Lehigh Valley cities, with approximately one-fourth of the population of the largest Lehigh Valley city, Allentown. In turn, this metropolitan area comprises Pennsylvania's third-largest metropolitan area.