The Chicago Hub Network is a collection of proposed fast conventional and high-speed rail lines in the Midwestern United States including of track. Since the 1990s, there have been multiple proposals to build a network from Chicago to destinations such as Milwaukee, Madison, Minneapolis, Indianapolis, Detroit, Kansas City, St. Louis, Cleveland, Cincinnati, and Louisville. In addition, the rail lines from the Chicago hub would connect through to cities in Canada. Eastern routes from Chicago would also blend into the Ohio Hub network. In addition to providing better connections between Midwestern cities, the projects are intended to reduce or eliminate the operating subsidies that American passenger train routes currently require. If implemented, the plans would have some of the nation's fastest trains in Chicago, as it had in the 1930s and 1940s when the Twin Zephyrs, Twin Cities 400, and Hiawatha were based in the city. Chicago is North America's largest rail hub, and remains unsurpassed in the total number of passenger and freight trains that converge on any city on the continent. Chicago is a major hub for Amtrak, with 15 different lines terminating at the city's Union Station. Most existing passenger trains in the region operate at speeds of about , although a few travel faster. The various plans have suggested speeds ranging from for the core routes, as well as improved speeds for secondary routes. The Chicago–St. Louis rail line is being upgraded so passenger trains will be able to reach top speeds of when traveling between Joliet and Carlinville. Early studies and ISTEA corridors Renewed interest in high-speed rail occurred by the year 1990 when the Minnesota–Wisconsin–Illinois Tri-State Rail Study was underway. A Chicago–Milwaukee–Madison–La Crosse–Rochester–Twin Cities "southern corridor" (a variation of the former Hiawatha routing) and a Chicago–Milwaukee–Green Bay–Wausau–Eau Claire–Twin Cities "northern corridor" were described in a preliminary report in December of that year. A final report was released in May 1991 and recommended TGV-class service since it provided the greatest benefit to riders and others in the corridor, though a slower (and less expensive) "Amtrak upgrade" option was also deemed reasonable for capital-constrained investments. The Intermodal Surface Transportation Efficiency Act of 1991 (ISTEA) was passed on December 18, 1991, and requested designation of up to five corridors. A core of what would become the Chicago Hub Network was the first of these five to be announced by Secretary of Transportation Andrew Card on October 15, 1992,