The Sunshine Special was inaugurated by the St. Louis, Iron Mountain and Southern Railway, (later the Missouri Pacific Railroad), on December 5, 1915, to provide a premium level of passenger train service between St. Louis, Little Rock, and destinations in Texas. Until being shifted into a secondary role by the Texas Eagle diesel powered streamliner in August 1948, the Sunshine Special served as the flagship of the Missouri Pacific Railroad's passenger train service. The last vestige of the Sunshine Special name did not disappear from Missouri Pacific timetables until 1962.
Between July 7, 1946, and April 25, 1948, the Missouri Pacific and the Pennsylvania Railroad operated the Sunshine Special jointly between New York City and Texas. Low traffic west of St. Louis prompted the Missouri Pacific to withdraw from the joint operation in favor of exchanging sleeper cars. The PRR renamed its train the Texas Eagle on August 15, then finally the Penn Texas on December 12.
The Sunshine Special was thrust into the national spotlight on January 22, 1927, when it struck a bus carrying members of the Baylor University basketball team in Round Rock, Texas. According to reports, the bus driver, 19-year-old Joe Potter, failed to see the train approaching the crossing at nearly sixty miles per hour from the bus' right. When Potter did see the train, he felt he had no choice but to attempt to beat it across the tracks. Attempting to put more distance between the bus and the train, Potter veered to his left, moving the bus farther ahead of the train. The results were disastrous, with ten Baylor students killed. The tragedy gave rise to Baylor's longstanding tradition of remembering "The Immortal Ten."