The M&B is owned by Genesee and Wyoming Inc. After Hurricane Katrina damaged the CSX mainline in Louisiana in 2005, it served as a run-through bridge route for CSX to connect with Union Pacific via the Kansas City Southern between Meridian and Shreveport, LA, thereby avoiding interchange at New Orleans. Due to the volume of trains being handed over to the M&B, the railroad suffered severe crew shortages throughout the timespan of the detours. CSX trains could be found sitting idle at both ends of the railroad awaiting crews. These problems were further enhanced by the horrible track conditions on the M&B mainline, resulting in widespread 10mph slow orders. It routinely took 12 hours or more for a single train to traverse the entire route. Due to the abnormal curvature prevalent on the mainline, the M&B stipulated that all 6-axle locomotives on these trains be equipped with radial trucks to reduce rail wear and prevent derailments. In September 2007, all remaining interchange between KCS and CSX via the M&B was moved to other lines. This was due in part to the stipulation that no CSX trains would be allowed to run via the KCS after the joint NS/KCS Meridian Speedway venture was completed.
In 2003 the M&B took over the ex-L&N line from Myrtlewood to Selma, Alabama and the ex-Western Railway of Alabama line from Selma to Burkeville. CSX retained ownership between Montgomery and Burkeville, where there is a large industrial customer.