The Municipal Harbor Belt Railroad was constructed by the municipal government on the perimeter of the upper harbor for hauling freight between businesses in this area and the trunk lines of the Baltimore and Ohio, Western Maryland, and Pennsylvania railroads. Complaints of heavy switching charges for the interchange of freight cars from one line to another, port development, and the attraction of industries to this area supported the construction of this railroad. The line was a distance of only 3.57 miles from the former connection with the Pennsylvania Railroad in Aliceanna Street to the connection with the Baltimore and Ohio and the Western Maryland railroads in McComas Street. From this main track, numerous spurs extended onto the property of various businesses such as the McCormick Spice and Bethlehem Steel companies.

In the summer of 1913 the board of estimates authorized the construction of the first section of the railroad, a single track on Key Highway from Lawrence to Light Streets. This section was completed by May 1915 and construction on sections two and three (down Light Street to Pratt, Pratt to East Falls Avenue, and East Falls to Aliceanna Street) began. The Baltimore and Ohio took over formal operation of each section as it was opened to traffic even though the city was responsible for the actual construction, construction expense, and it's ownership. The railroad was completed in 1918 with the municipal government intending to operate the line itself.

In 1921 Mayor Broening solicited suggestions for an operating plan from executives of the Baltimore and Ohio, Western Maryland, and Pennsylvania railroads and received replies that the line could not be run at a profit by either the railroads or the city, that the streets traversed by the railroad were too congested, and that the curves in the track were too steep for standard railroad equipment. However, a connection was made with the Western Maryland railroad and a ninety-day operating test undertaken with a committee of four — the city highways engineer and one representative from each of the three railroads — supervising operation, the railroads footing the operating costs, and the city covering maintenance charges. This "experiment" lasted until the summer of 1946 when the three carriers assumed responsibility for both operation and maintenance of the Municipal Harbor Belt Railroad, with the Baltimore and Ohio serving as the agent for the other two roads. Prior to this, the city expended approximately five thousand dollars per year for maintenance but the need for major repairs had become increasingly apparent. Under the terms of the 1946 agreement the city retained ownership of the line but the three roads gained the right to rehabilitate, maintain, use, and operate railroad and consented to undertake the deferred maintenance work.

In 1973 the ends of the line (Pratt to President Street and north of McCormick Company) were abandoned. But the Riverside Yard (Fort and Lawrence Streets) to the McCormick section is still in operation at the present time, under the control of the Baltimore and Ohio. For further information consult the Enoch Pratt Free Library, Maryland Room, Vertical File under "Baltimore Municipal Harbor Belt Railroad" and ord. 527 (1946).