Since opening in 1976, the Metro network has grown to include six lines, 91 stations, and of route. The rail network is designed according to a spoke-hub distribution paradigm, with rail lines running between downtown Washington and its nearby suburbs. The system makes extensive use of interlining: running more than one service on the same track. There are six operating lines. The system's official map was designed by noted graphic designer Lance Wyman and Bill Cannan while they were partners in the design firm of Wyman & Cannan in New York City.