The seat of La Salle County, the city lies on I-35 in the northwestern part of the county. It was named for Joseph Cotulla, a Polish immigrant, who established the town site upon learning that the International-Great Northern Railroad was extending its railroad line through La Salle County. Its economy has been largely based on cattle and sheep ranching. Oil discovered in the 1950s helped boost the economy. Lyndon B. Johnson and short-story writer O. Henry once called Cotulla home.