HOV lanes have been around since 1969 when a bus-only lane opened in northern Virginia on I-395. Population growth in the nation's major metropolitan areas fueled an HOV growth spurt in the 1980s and 1990s.
According to the California Department of Transportation, the lanes move a high number of people, not vehicles.
HOV lanes have diamonds painted on the surface to distinguish them from normal traffic lanes. Most are on the far left in each direction of traffic.
Thirty metropolitan areas in the U.S. have HOV lanes. They include Atlanta, Seattle, Washington, D.C., New York, Los Angeles, Dallas, San Francisco and Houston.
HOV lanes encourage carpooling and reduce traffic congestion.
