The Usumacinta River in southeastern Mexico and northwestern Guatemala, formed by the junction of the Pasión River, which arises in the Sierra de Santa Cruz (in Guatemala) and the Salinas River, also known as the Chixoy, or the Negro, which descends from the Sierra Madre de Guatemala, is the border between Chiapas, Mexico and Guatemala. Yaxchilan, one of the most powerful cities of the Classic Maya lies along its banks.

Before roads penetrated the jungle, such as the Border Highway constructed by the Mexican Government in the early 1990's, the river was the only means of travel in this region. Huge trunks of hardwood trees are floated downriver to Tabasco State.

In the 1980's, many Guatemalan refugees fled across the river to relative safety in Mexico.