As its name implies, the Oklahoma City, Ada and Atoka Railway (OCA&A) ran through the gentle rolling hills and pastures of central and southeastern Oklahoma, connecting the towns of Atoka and Ada to Oklahoma City via Shawnee. Other towns along the route included Midway, Lehigh, Coalgate, Centrahoma, Tupelo, Stonewall, Konowa, Maud, Harjo, Woods, Marion, and Barnard. The railroad was formed from track that was not included in the 1923 reorganization of the Missouri-Kansas-Texas Railroad.
According to the History of Pontotoc County, the railroad began as a KATY extension from Atoka boasting four passenger and four freight trains per day serving Pontotoc County. With the closing of the coal fields in Coalgate and uncertain economic times, the KATY sold the railroad in 1923 to Mr. H. R. Hudson, changing the name to the OCA&A. Atlantic (4-4-2) engines and Pacifics (4-6-2) were used on the line at this time. Coaling towers were located in Konowa and Tupelo, so only a water tower and wye were needed in Ada. In addition to passengers and their personal property, revenue was generated through the transport of poultry, cattle, dry ice, and cement.
In 1929, the OCA&A joined the Muskogee Company (which also controlled the Midland Valley and the KO&G). In 1964, the OCA&A was sold to the Missouri Pacific's Texas and Pacific Railway which operated it until selling it to the AT&SF Railway.