The river that forms part of the border between the United States and Mexico is the Rio Grande. This river runs approximately 1,885 miles, originating in the San Juan Mountains of Colorado and flowing into the Gulf of Mexico. It has been historically significant for trade and cultural exchange between the two nations. Over the years, the Rio Grande has faced environmental challenges, including water allocation disputes and pollution. It serves as both a natural boundary and a vital water source, impacting ecosystems and communities along its banks.