The company was founded in 1897 as the Carrollton Short Line Railway to link the city of Carrollton, Alabama with the Mobile and Ohio Railroad at Reform, Alabama. Through mergers, acquisitions and the building of track, the railroad eventually reached the port of Mobile, Alabama. In 1948, the railroad was purchased by the Frisco, who operated it as a separate entity until 1971, when it was absorbed into the parent company.
In 1950, under the auspices of the ATN, the Frisco began freight service to and from, and on Blakeley and Pinto Islands by way of two car floats across the Mobile river. The service was continued after the SLSF was merged into the BN, until about 1994.
In 1897 the Mobile & Ohio Railroad chose to route through Pickens County, Alabama by way of Reform, Alabama — rather than the county seat of Carrollton — since the Reform route would be faster. Having failed in their appeal to the M&O, leading citizens of Carrollton set up a corporation to connect their city with the railroad; this was chartered by the State of Alabama as the Carrollton Short Line Railway in June 1897. John Taylor Cochrane, who had constructed the Tuscaloosa Belt Line, began building this new railroad.
In 1925 AT&N reported 15 million ton-miles of revenue freight on 187 miles of line; in 1967, 543 million ton-miles on 214 route-miles.