The Nueces Strip or Wild Horse Desert is the area of south Texas between the Nueces River and the Rio Grande. The Republic of Texas claimed the Rio Grande as its southern border; Mexico claimed the Nueces River (150 mi or 240 km north of the Rio Grande). The area between the two rivers became known as the Nueces Strip. Both countries invaded it, but neither controlled it nor settled it. It was the scene of the first fighting in the Mexican–American War in 1846. In the Treaty of Guadalupe Hidalgo, signed in 1848, Mexico ceded the Nueces Strip to the U.S.