The Missouri Pacific Railroad owned and operated a fleet of more than 1,500 diesel locomotives and was a pioneer in the early days of computer-guided rail technology. It was a major hauler of grain, trailers on flat cars, coal, ore, autos and dry goods. When they merged in 1982, the MoPac owned newer locomotives, owned more locomotives and operated more track than partner Union Pacific Railroad (UP). The Missouri Pacific had merged with the Union Pacific and Western Pacific Railroad companies to create the largest system in its day, the “Pacific Rail Systems,” under the holding company Union Pacific Corporation, but kept its own corporate and commercial identity. In December of 1989, the Missouri-Kansas-Texas and the Galveston, Houston & Henderson were both merged into the Missouri Pacific after the Union Pacific acquired them in 1988. By 1994 all motive power of the Missouri Pacific was repainted and on January 1, 1997, its corporate and commercial identity officially merged into the Union Pacific. The Union Pacific continued to use the MoPac headquarters building in downtown St. Louis for its customer service center until February of 2005.