Sahara, the vast desert of northern Africa, and the world's largest arid region. It occupies much of the broad northern half of Africa and covers some 3,500,000 square miles (9,000,000 km2), an area only slightly less than that of the United States.

The northern boundaries of the Sahara are the Atlas Mountains and, in Egypt and parts of Libya, the Mediterranean Sea. From there the desert stretches 1,200 miles (1,900 km) southward to about 17° north of the Equator.

From the Red Sea on the east to the Atlantic Ocean on the west the Sahara stretches more than 3,500 miles (5,600 km)—farther than from New York to Los Angeles.