Gray Line Worldwide operates local sightseeing tours across the world using trolley coaches, double-deckers and standard single deck coaches. It also offers charter services, airport transfers and convention services.
Gray Line has a presence in over 150 locations around the world. In 2004 its carriers handled some 25 million passengers.
The company was founded in 1910 by restaurateur Louis Bush, who refurbished a Mack Truck and offered tours of Washington, D.C. It is currently based in Denver, Colorado.