King County Metro, or Metro for short, is the public transit authority of King County, Washington, a division of the King County Department of Transportation. It began operations on January 1, 1973, but can trace its roots to Seattle Transit, founded in 1939, and Overlake Transit Service, founded in 1927. As of 2014, it operated 1,835 buses on 209 routes. Its annual ridership in 2012 was over 114 million making it the 8th largest agency in the nation.