In 1865 the Union Pacific Railway Southern Branch was incorporated to build a railroad from the St. Louis-Kansas City area to the Gulf of Mexico. In 1870, with construction completed to the border of Indian Territory, the line was renamed the Missouri, Kansas & Texas Railroad. This title was often shortened to M-K-T, which led to the familiar nickname by which the line is best known — "The Katy."
Following the route of an old cattle trail, the Katy became the first railroad to cross Indian Territory, now the State of Oklahoma, and enter Texas from the north. On Christmas Day 1872, over 100 passengers rode the first Katy train into Denison, a new townsite named for M-K-T Vice President George Denison. The construction and acquisition of branch lines soon extended the Katy east to Greenville, west to Rotan and Wichita Falls, and south to Galveston and San Antonio. By 1904, the system had over 1,000 miles of track in Texas. The railroad transported cattle, cotton, and other crops to market. It also carried passengers on such trains as the "Texas Special" and the "Katy Flyer" before passenger service ended in 1965.
Today (1975) Denison is a division headquarters on the M-K-T and the home of about 600 railroad employees.