The Algodones Dunes is a large erg (sand dune field) located in the southeastern portion of the U.S. state of California, near the border withArizona and the Mexican state of Baja California. The field is approximately 45 miles long by 6 miles wide and extends along a northwest-southeast line that correlates to the prevailing northerly and westerly wind directions. The name "Algodones Dunes" refers to the entire geographic feature, while the administrative designation for that portion managed by the Bureau of Land Management is the Imperial Sand Dunes Recreation Area (sometimes called the Glamis Dunes).