Their mainline ran in what is now the west metro of the Twin Cities. It went from MNS Junction in Crystal, through New Hope, Golden Valley, St Louis Park, Bloomington, Savage, Lakeville and down to Northfield. They had shops at Glenwood on a spur line that went from the present area of Hwy 100 and Hwy 55 to the edge of downtown Minneapolis. There was also a line from Auto Club Junction in Bloomington through Richfield and into south Minneapolis. Besides its freight service, the company ran a passenger service in its early years from Minneapolis to Antlers Park, a picnic destination they developed. Antlers Park is now part of the Lakeville city park system.

Today much of the same track, and even some of the same locomotives and cabooses, are in service as a part of Progressive Rail.

The line is still operated in the 21st century by Conrail under the CSX/NS Shared Assets arrangement, and has about six customers. The line now terminates at U.S. Route 1 in East Brunswick, New Jersey, near New Brunswick. Many of its spurs have been abandoned.

The impetus for the NOPB came during the turn of the century era when multiple railroads terminating locally created both congestion at the Port of New Orleans and safety problems on city streets. The railroad began operation in 1908 with the intention of giving the major railroads "uniform and impartial" access to the port.

The railroad is managed by the Public Belt Railroad Commission, which also owns and maintains the Huey P. Long Bridge, the longest railroad bridge in the world. NOPB covers over 160 kilometers (100 mi) of track with eight locomotives, over 250 boxcars and 65 gondola cars. No funding is received from the city; operating and capital expenses are covered by operating revenues.

Hurricanes Katrina and Rita in 2005 caused an estimated $450 million in damage to NOPB equipment and track. At least 70 percent of the railroad's lines and interchanges were back in operation by September 2005, and 90 percent by March 2006.

The Bay Colony railroad was chartered on March 31, 1977, with the intent of taking over freight service on former New Haven lines from Conrail, which was planning to abandon service. Bay Colony took over all freight operations on the lines on June 12, 1982. It currently operates a fleet of approximately 7 secondhand locomotives.