Coplay is a borough in Lehigh County, Pennsylvania, six miles (10 km) northwest of Allentown. It is part of the Lehigh Valley region of the state. In 1900, 1,581 people lived in Coplay; in 1910, 2,670 people lived there. The population was 3,387 at the 2000 census. Coplay is included in the Allentown-Bethlehem-Easton, PA-NJ Metropolitan Statistical Area, which is also included in the New York City-Newark, New Jersey, NY-NJ-CT-PA Combined Statistical Area.