Petersburg is a small unincorporated community in southeastern Springfield Township, Mahoning County, Ohio, United States. It is part of the Youngstown-Warren-Boardman, OH-PA Metropolitan Statistical Area. The community was founded in the 1790s by German immigrants from Pennsylvania. Including those from Pennsylvania was Peter Musser, Israel Warner and family who are now buried outside of Petersburg in the Old Springfield Township Cemetery along with the Rudesil family and other early families. Petersburg was named after Peter Musser by his son, Peter Musser Junior, before most of the Musser children migrated to other parts of Ohio and to Missouri. Petersburg's post office was called "Subrosa" at one point in the early history and the first Post Master was Jacob Musser, the only son of Peter to stay in Petersburg and was noted to be the first "Squire" of Petersburg. Petersburg used to be the principle village of Springfield township early in its history. Many business that were in Petersburg included the Petersburg Grain Mill, Petersburg Creamery, a butcher shop, a coffin shop, a millinery, a drug store, 2 grocery stores, a liquor store, a blacksmith shop, three churches, a barber shop, a veterinarian, a violin maker, Warner's Inn, the Mahoning House, Petersburg Inn, Knesal's Hardware,and many other little shops of general merchandise. The building that was once used as the Petersburg Inn burned to the ground around 1955 and was believed to have been built around 1800. A few other significant historical buildings in the community were St. John's Lutheran Church and the Petersburg Presbyterian Church that were founded by early settlers of that area including the following families: Wallace, Musser, Smith and Kneasel. Petersburg is located at the intersection of State Routes 170 and 617. It is skirted by Interstate 76.