what county is mcallen texas in
HomeâRGV CitiesâHidalgo CountyâMcAllen Texas. McAllen Texas is the twentieth most populous city in Texas as well as largest city in Hidalgo County, Texas, United States. It is located at the southern tip of Texas in an area known as the Rio Grande Valley and is part of the American South. Its southern boundary is located on the Rio Grande River across the Mexican city of Reynosa, the Rio Grande, and about 70 miles (110 km) west of South Padre Island and the Gulf of Mexico.