Amistad Dam is a large dam across the Rio Grande

Rio Grande

The Rio Grande is a river that flows from southwestern Colorado in the United States to the Gulf of Mexico. Along the way it forms part of the Mexico – United States border. Its length varies as its course changes...

 on the United States-Mexico border. It serves to store water for irrigation and generate hydroelectricity. The dam was first proposed in a 1944 treaty between the United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 and Mexico

Mexico

The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...

. Construction began in 1963 and was finished in 1969, with the hydroelectric plants constructed in the 1980s. Of the dam's roughly US$72 million cost, Mexico shouldered about 4/7 of the funds and the United States about 3/7. At roughly 5 miles (8 km) long, the dam lies mostly on the Mexican side of the border and forms Amistad Reservoir

Amistad Reservoir

Amistad Reservoir is a reservoir on the Rio Grande at its confluence with the Devils River 12 miles northwest of Del Rio, Texas, USA. The lake is bounded by Val Verde County on the Texas side of the international border, and the state of Coahuila on the Mexican side of the border...

.