The Lehigh Valley , known officially by the United States Census Bureau and the United States Office of Management and Budget as the Allentown-Bethlehem-Easton, PA-NJ Metropolitan Statistical Area and referred to informally and locally as The Valley is a metropolitan region officially consisting of Carbon, Lehigh and Northampton counties in eastern Pennsylvania and Warren county on the western edge of New Jersey, in the United States. The Lehigh Valley's largest city, with a population of 119,104, is Allentown.