Texas-Location, size, and extent. Located in the west south-central US, Texas is the largest of the 48 conterminous states.Texas's US rank slipped to 2nd when Alaska entered the Union in 1959. The total area of Texas is 266,807 sq mi (691,030 sq km), of which land comprises 262,017 sq mi (678,624 sq km) and inland water 4,790 sq mi (12,406 sq km).arge islands in the Gulf of Mexico belonging to Texas are Galveston, Matagorda, and Padre. The boundary length of the state totals 3,029 mi (4,875 km), including a general Gulf of Mexico coastline of 367 mi (591 km); the tidal shoreline is 3,359 mi (5,406 km).