Harlingen is a city in Cameron County in the central region of the Rio Grande Valley of the southern part of the U.S. state of Texas, about 30 miles from the coast of the Gulf of Mexico. The city covers more than 40 square miles and is the second-largest city in Cameron County, as well as the fourth-largest in the Rio Grande Valley. As of the 2020 census, the city had a population of 71,892.