Defining the Borders: The Four Boundaries of Texas

Texas, the second-largest U.S. state by both area and population, shares its borders with four U.S. states and the country of Mexico. Its distinct shape is defined by the following boundaries:

North: The Red River and the Panhandle

The northern border separates Texas from Oklahoma. The eastern portion follows the Red River, while the western "Panhandle" section runs along a straight longitudinal line bordering Oklahoma's western edge.

South: The Rio Grande

The entire southern boundary is an international border with Mexico, defined almost entirely by the Rio Grande (Río Bravo del Norte). The river flows from El Paso in the west to the Gulf of Mexico at Brownsville in the east.

East: The Sabine River and Gulf Coast

The eastern border separates Texas from Louisiana (north) and Arkansas (a small section in the northeast). The Sabine River forms a significant natural boundary between Texas and Louisiana, flowing into Sabine Lake and the Gulf of Mexico.

West: The Desert Border

The western border runs along a meridian line separating Texas from New Mexico. This arid stretch runs from the northwest corner of the Panhandle down to the tri-point near El Paso where Texas, New Mexico, and Mexico meet.

These boundaries encompass 268,596 square miles of diverse geography, from piney woods and prairies to desert basins and coastal wetlands.