The railroad was chartered on March 17, 1870, by the
United New Jersey Railroad and Canal Companies for the sole purpose of tying up the construction of the National Railway. In 1873, the M&S had plans to straighten out the line as part of a new through railroad operated by the PRR. No straightening was done, but it did become PRR-operated. The railroad was formally opened on February 6, 1874, with an
excursion train from Millstone to
Trenton. At the beginning, it was leased by the
United New Jersey Railroad and Canal Company and operated by the
Belvidere Delaware Rail Road. By mid-1875, the railroad was being operated by the PRR as their Mercer and Somerset Branch, part of a through route from New York. The M&S served as one of several legal challenges to the
National Railway line from Philadelphia to New York. Others were the
Philadelphia, Newtown and New York Railroad in Pennsylvania and a fight over whether they had the right to cross the
Delaware River. The New Jersey-side one resulted in a
frog war at
Hopewell in early 1876. The National Railway won the battle, and the Delaware and Bound Brook Railroad formally opened on April 27, 1876. The M&S was sold under
bankruptcy to the
Pennsylvania Railroad on November 28, 1879. The alignment was officially abandoned by the Pennsylvania on January 29, 1880. It was soon dismantled, since it no longer served its purpose to block the National Railway. The abandoned grade of the west end of the line became Jacobs Creek Road. == Station listing ==