The Rio Grande River qualifies as such.
The Nueces River qualifies as such. This ill-defined border resulted in several skirmishes, which in turn became the perfect pretext to start the Mexican-American War (1846-1848).
The Nueces River
The Neches river
The Rio Grande
Mexico claimed that the Nueces River was the boundary between the two nations while the US maintained that the Rio Grande was the boundary. As clear boundary definitions were never established, some skirmishes occurred on this no-man's land, resulting in American blood shed, and used as casus belli by President Polk to start the Mexican-American War (1846-1848).
Right.
Rio Grande River
The border
Mexico claimed the Nueces River defined the US-Mexico border.
The Mexican war started over boundary disputes between the United States and Mexico. The Mexicans claimed that the boundary lied near corpus Christi and the U.S claimed it was the Rio Grande.
MEXICO owend it
Nueces River and the the Rio Grande River. Mexico claimed that the Nueces river was the Texas and Mexico border. The US claimed that the Rio Grande was the correct location.
The US claimed what became the New Mexico territory during the Mexican-American War. It was primarily a linear western extension from Texas.
The Treaty of Guadalupe Hidalgo settled the boundary dispute between the United States and Mexico.
Most of the Mexico-Belize border is defined by the Hondo River (Spanish: Rio Hondo).There is however, a Rio Hondo located in the US State of New Mexico, but it doesn't define any boundary with the country of Mexico.