McAllen is the largest city in Hidalgo County, Texas, United States, and the 21st-most populous city in Texas. It is located at the southern tip of the state in the Rio Grande Valley, close to the country of Mexico. The city limits extend south to the Rio Grande, across from the Mexican city of Reynosa. McAllen is about 70 mi (110 km) west of the Gulf of Mexico. As of 2019, McAllen's population was estimated to be 143,268. It is the fifth-most populous metropolitan area (McAllen–Edinburg–Mission) in the state of Texas, and the binational Reynosa–McAllen metropolitan area counts a population of nearly 1.52 million.From its settlement in 1904, the area around McAllen was largely rural and agricultural in character, but the latter half of the 20th century had steady growth, which has continued in the 21st century in the metropolitan area. The introduction of the maquiladora economy and the North American Free Trade Association led to an increase in cross-border trading with Mexico.

Corpus Christi (; Ecclesiastical Latin: "Body of Christ") is a coastal city in the South Texas region of the U.S. state of Texas and the county seat and largest city of Nueces County, it also extends into Aransas, Kleberg, and San Patricio Counties. It is 130 miles southeast of San Antonio. Its political boundaries encompass Nueces Bay and Corpus Christi Bay. Its zoned boundaries include small land parcels or water inlets of three neighboring counties. The city's population was estimated to be 326,586 in 2019, making it the eighth-most populous city in Texas. The Corpus Christi metropolitan area had an estimated population of 442,600. It is also the hub of the six-county Corpus Christi-Kingsville Combined Statistical Area, with a 2013 estimated population of 516,793. The Port of Corpus Christi is the fifth-largest in the United States. The region is served by the Corpus Christi International Airport. The city's name means body of Christ in Ecclesiastical Latin, in reference to the Christian sacrament of Holy Communion. The name was given to the settlement and surrounding bay by Spanish explorer Alonso Álvarez de Pineda in 1519, as he discovered the lush semitropical bay on the Western Christian feast day of Corpus Christi.

Harlingen ( HAR-lin-jin) 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 (48 km) from the coast of the Gulf of Mexico. The city covers more than 40 square miles (104 km2) and is the second-largest city in Cameron County, as well as the fourth-largest in the Rio Grande Valley. As of the 2010 census, the city had a population of 64,849, for a growth rate of 12.5% since the 2000 census.Harlingen is a principal city of the Brownsville–Harlingen metropolitan area, which is part of the larger Brownsville-Harlingen-Raymondville combined statistical area, included in the Matamoros–Brownsville metropolitan area.