Mark,
Awhile back, you wanted to know about the railroads in Texas. from the Gulf Coast Railroad Historical Society here are the following railroads that made it into the Houston area or were in some way connected to Houston by consolidation.
first railroad - Buffalo, Brazos,& Colorado - 1851
Galveston & Red River - 1853
Houston & Texas Central - 1856
Houston Tap- 1856
Houston Tap & Brazoria - 1858
Galveston, Houston & Henderson - 1856
Texas & New Orleans - 1861
Galveston, Harrisburg, & San Antonio - 1868
Houston & Great Northern - 1871
Western Narrow Gauge - 1871 (Texas Western Narrow Gauge) - 1874
International & Great Northern - 1876
St. Louis, Iron Mountain & Southern - 1879
Gulf, Colorado & Santa Fe - 1880
Houston & Brazos Valley - 188?
Burlington - Rock Island - 188?
San Antonio & Aransas Pass - 1893
Houston, East and West Texas - 1894
Houston Belt & Terminal -192?
Port Terminal Railroad Association - 192?
Public Harbor Belt 1924
Galveston - Houston Electric - 1911
Houston North Shore - 1927
Ft. Worth & Denver - 1965
class 1 railroads in Texas consolidated the above railroads by 1920 - present
Santa Fe
Burlington Northern
Southern Pacific
Rock Island
Union Pacific
Missouri, Kansas & Texas
Missouri Pacific
Kansas City Southern
Texas Mexican Railroad
hope this helps, …chuck