Harlingen is a city in Cameron County in the heart of the Rio Grande Valley of south Texas, United States, about 30 miles (48 km) from the coast of the Gulf of Mexico. The city covers more than 34 square miles (88 km), and is the second largest city in Cameron County and the third largest in the Rio Grande Valley, after Brownsville and McAllen. As of the 2000 census, the city had a total population of 57,564. Harlingen is a principal city of the Brownsville–Harlingen Metropolitan Statistical Area, which is part of the larger Brownsville–Harlingen–Raymondville Combined Statistical Area.