State Highway 99 traces its roots back to the first State Highway 48, which was first established on January 19, 1927. This highway connected Ada to Holdenville; it roughly followed present-day SH-99 until about 2 miles north of the Canadian River, it then turned east and passed 1 mile south of the unincorporated town of Vamoosa, after which it followed the route of today's SH-56. After 10 miles, it passed through Sasakwa, in which it turned north and ended at the original SH-3, at the intersection called "Five-Mile Corner", west of Holdenville. The 1928 state highway map shows the highway extended to SH-9 (now US-62) near Prague along the present-day SH-99 alignment, with the Canadian River crossing as a toll bridge. By January 1, 1929, the route had been realigned to pass through Konawa. The old designation between the Canadian River and SH-3 was replaced shortly after by SH-56.