National (CN) Railroad. The CN cars were huge by the standards of the time: each 75-footer (23.86 m) could carry eight vehicles, which were loaded through end-doors. The Auto-Train began running on December 6, 1971. It was immediately popular with the traveling public and at first enjoyed financial success as well. In FY1974 the company turned a profit of $1.6 million on revenues of $20 million. In May 1974, service began over a second route between Florida and Louisville, Kentucky, and the company was mulling additional service between Chicago and Denver. The Louisville extension proved to be the company's undoing. The decaying Louisville and Nashville Railroad track between Louisville and Florida (which also hampered Amtrak's Floridian) hindered operations, and a pair of derailments stretched the company's finances to the breaking point. Service ceased in April 1981. Amtrak After 22 months, the service was revived by Amtrak, which operates most intercity passenger trains in the United States. Amtrak acquired the terminals in Lorton and Sanford and some of the Auto-Train equipment. On October 30, 1983, it introduced a triweekly version of the service under the restyled name "Auto Train". Daily service was introduced a year later. Amtrak used Auto-Train's bi-level and tri-level autoracks. For passenger equipment, it initially used a mixture of former Auto-Train railcars and mid-century long-distance railcars from Amtrak's general fleet, all rebuilt to Amtrak's "Heritage Fleet" standards. In the mid-1990s, Amtrak replaced all these passenger railcars, which were of the conventional single-level type, with its newer, bi-level Superliner I and II equipment. In 2006, the aging bi-level, tri-level, and "van" autoracks were phased out and replaced with 80 new autoracks. Unlike the old racks, the new racks have uniform heights and are most similar to the "vans" of the previous fleet. Amtrak operates two Auto Trains simultaneously each day, Train No. 53 from Lorton and Train No. 52 from Sanford, departing at 5 p.m. for a scheduled arrival the following day at 10 a.m. In practice, however, the trains usually run late. In May 2021, for example, only 31 percent of Auto Trains arrived on time, mostly because of interference by freight trains that have preference over much of the route. The Auto Train was the last Amtrak service to permit smoking on board. Amtrak discontinued the practice on June 1, 2013. Auto Train operates on the same route it and its predecessor have always used; most of