The borough of Mars was founded in 1873, and is situated about halfway between the cities of Pittsburgh and Butler. The small community is nestled in a small valley along Breakneck Creek with PA 228 located about a mile south of Mars, and the Mars-Evans City Road located to the north. It is home to the popular roadside attraction, the Mars "Spaceship" or "Flying Saucer". It is also home to the Mars Station which is one of the last railroad depots still standing from the now defunct Pittsburgh and Western Railroad.
In 1873, Samuel Parks constructed a home and a water-powered gristmill along Breakneck Creek. Parks then decided to have a post office placed in his home, so he received help from his friend, Samuel Marshall to help establish it. The name of the post office became Overbrook. In 1877, the Pittsburgh, New Castle and Lake Erie Railroad was constructed through Overbrook, and had a station built there. In 1882, the name of the community was changed to Mars since the railroad already had a stop with the name, "Overbrook". No one is sure how the name "Mars" came into being. Some say it was Park's wife who enjoyed astronomy, or it was shortened after Samuel Marshall's name. On March 6, 1895, Mars was incorporated as a borough.
In 1904, the Pittsburgh and Butler Street Railway gained permission from Mars to construct its right-of-way through the borough. The line become part of the Pittsburgh, Harmony, Butler and New Castle Railway in 1917, being renamed Pittsburgh, Mars and Butler Railway. The line closed in 1931.
The was named after the borough. The ship became part of the United States Pacific Fleet in 1963, and was decommissioned in 1998. It was then sunk in 2006 as a target vessel. The bell of the USS Mars was donated to the borough, and has become a permanent memorial in the downtown park.