The Texas Triangle is a region of Texas that contains the state's five largest cities and is home to the majority of the state's population. The Texas Triangle is formed by the state's four main urban centers, Austin, Dallas-Fort Worth, Houston, and San Antonio, connected by Interstate 45, Interstate 10, and Interstate 35. In 2020, the population of the Texas Triangle reached nearly 21 million following rapid growth across much of Texas. The Texas Triangle is one of eleven megaregions in the United States, clusters of urban areas that share economic and cultural ties.

Houston is the most populous city in the U.S. state of Texas and in the Southern United States. Located in Southeast Texas near Galveston Bay and the Gulf of Mexico, it is the seat and largest city of Harris County; as well as the principal city of the Greater Houston metropolitan area, which is the fifth-most populous metropolitan statistical area in the United States and the second-most populous in Texas after Dallas–Fort Worth. With a population of 2,302,878 in 2022, Houston is the fourth-most populous city in the United States after New York City, Los Angeles, and Chicago, and the seventh-most populous city in North America. Houston is the southeast anchor of the greater megaregion known as the Texas Triangle.