McAllen is a city in the U.S. state of Texas. It is located at the southern tip of the state in the Rio Grande Valley, on the Mexican border. The city limits extend south to the Rio Grande, across from the Mexican city of Reynosa. As of the 2024 census estimate, McAllen's population was 148,782, making it the most populous city in Hidalgo County, the second most populous city in the Rio Grande Val…