The Hoover Dam sits on the Colorado River between the states of Arizona and Nevada, and provides electrical power throughout the Southwest.

Photograph by George F. Mobley, National Geographic
  • On October 9, 1936, Hoover Dam began transmitting electricity to Los Angeles, California. The dam sits 428 kilometers (266 miles) away from the city, on the Colorado River between the states of Arizona and Nevada.

    The Hoover Dam was the largest concrete structure ever built. More than 5,000 workers poured more than 2.3 million cubic meters (3 million cubic yards) of concrete to construct the dam—enough to pave a highway between the East and West Coasts of the United States. The finished dam was 220 meters (725 feet) high and 379 meters (1,244 feet) long.

    The Hoover Dam continues to generate 4.2 million megawatt-hours of electricity every year. The generators in the dam provide much of the electricity used in Nevada, Arizona, and Southern California. The reservoir (Lake Mead) created by Hoover Dam provides freshwater to 8 million people in the American Southwest.

  • Term Part of Speech Definition Encyclopedic Entry
    concrete Noun

    hard building material made from mixing cement with rock and water.

    construct Verb

    to build or erect.

    dam Noun

    structure built across a river or other waterway to control the flow of water.

    electricity Noun

    set of physical phenomena associated with the presence and flow of electric charge.

    freshwater Adjective

    having to do with a habitat or ecosystem of a lake, river, or spring.

    generate Verb

    to create or begin.

    generate Verb

    to create or begin.

    generator Noun

    machine that converts one type of energy to another, such as mechanical energy to electricity.

    transmit Verb

    to transfer electrical energy in bulk.