While the M&O had been blocked from reaching Birmingham over the BS, it finally reached that city over trackage rights on the IC’s extension from Corinth, Mississippi to Haleyville, Alabama and then to Birmingham over the Southern Railway in 1908. This lasted until April 22, 1952. Over the objections of the IC, the Interstate Commerce Commission gave GM&O permission to use the routing over the L&N from Tuscaloosa.

Freight service
The M&O advertised through carload and package car connections from its northern stations to stations on the Montgomery District as well as to points beyond Montgomery. The M&O used its 100, 200, and 300 series 4-6-0 Ten-wheel steam locomotives for freight and passenger trains. In freight service, two of these engines would often doublehead on freight trains due to the many steep hills on the Pea Vine. The district was the last stronghold of these engines due to the lightweight bridge and trestle load limitations. By the later 1930’s, the M&O began to strengthen the bridges and trestles to carry the heavier 2-8-2 400 series freight locomotives. Yet steam doubleheading lasted till the diesel electric locomotives came after World War II.

In the GM&O era, freight volume rose heavily, coming from northern and southern regions of the GM&O. Imported ore came from Mobile to Birmingham via Tuscaloosa. The GM&O also helped to locate a large paper mill at Prattville, Alabama. In the diesel era, GM&O hauled freight trains with the 700 series FA1 cab and booster units. The Montgomery District saw the last active GM&O steam locomotive regular assignment at Columbus, Mississippi. On October 15th, 1949 a diesel switcher replaced the steam engine at Columbus, marking the dieselization of the GM&O.

In the 1960’s, the railroad replaced the FA1’s with its 500 series General Motors GP30 units and 600 series GP35 units. In 1969, the new 700 series General Motors GP38AC units were assigned to the freights in sets of four. The train crews liked these the best for handling long and heavy trains on the Pea Vine. In the diesel era of the GM&O, Montgomery District freights grew to the maximum length and weight that could be handled, given locomotive horsepower and drawbar strength available. Locomotive engineers had to carefully apply the air brakes and throttle to keep freights stretched out and prevent trains breaking apart. The GM&O considered its Montgomery line profitable with a heavy volume of freight. The ICG used a motley group of diesels that train crews appraised with a low opinion. For a short time, the ICG tried to run a through Kansas City to Montgomery freight train. In 1985, the ICG ended freight service and sold the district’s trackage.