replace the grade crossings with overpasses. As originally constructed, the east end of the Air Line connected with the IC with connections that curved to the north to serve both Central Station and the yards and warehouses through downtown up to the Chicago River. There was a shorter, steeper ramp down for passenger trains to get into Central Station while a longer, less severe incline was used by freight trains. In 1968, a southward-facing connection was built, generally known as the South Leg because together with the original lines a wye was formed which was occasionally used to turn passenger trains around. The South Leg enables trains using the Air Line to travel directly to and from the south. After the coming of Amtrak in May 1971, the remaining passenger trains were gradually shifted from Central Station to Union Station and the northern connections were removed. This coincided with the gradual elimination of yards to the north (this area is the Illinois Center office, hotel, and retail complex today). Central Station closed in 1972 and was razed in 1974. Now the South Leg is the only connection from the IC mainline to the Air Line. The CB&Q has since become part of the BNSF Railway, and the C&NW is now part of the Union Pacific Railroad, each of which still owns a 1/4 share. The MCRR has sold its share to the Illinois Central Railroad, now owned by the Canadian National Railway. Amtrak's City of New Orleans, Illini, and Saluki utilize this line with a time-consuming switchback into Union Station from its west end. The Chicago Region Environmental and Transportation Efficiency Program (CREATE) is in the preliminary design phase for the Grand Crossing Project. This project will reroute the passenger trains from St. Charles Air Line to Norfolk Southern's Chicago Line in the Greater Grand Crossing neighborhood in Chicago. The CN also uses it as a freight connection. As of October 2021, a large project was nearing completion to replace a bridge passing over the future Wells Street Extension, and rebuild retaining walls on both lines between the 16th St. interlocking and the Chicago River. However, this section of the line has been inactive since May 2020 when the adjacent St. Charles Air Line Bascule Bridge crossing the river was elevated due to work on the west side of the river. The Canadian National Railway's employee timetable dated July 2011