WSM (branded The Legend) is a 50,000 watt AM radio station located in Nashville, Tennessee. It broadcasts a full-time country music format at 650 kHz and is known primarily as the home of The Grand Ole Opry, the world's longest running radio program. The station's clear channel signal can reach much of North America and nearby countries, especially late at night. It is one of two clear-channel stations in North America, along with CFZM/Toronto, that still primarily broadcast music. Nicknamed "The Air Castle of the South," it shares its callsign with WSM-FM, also in Nashville, and formerly with television Channel 4, now WSMV.