Carthagena Black Cemetery, also known as Union Cemetery, survives as a remnant of about 70 documented rural black and mulatto settlements established across Ohio before the Civil War. After the Cincinnati riots against blacks in 1829, Quaker abolitionist Augustus Wattles led 15 black families north in 1835 to settle in Mercer County, bought 189 acres in 1837, and had set aside this cemetery by 1840, the date of its oldest remaining headstone. In 1840, early mulatto settler Charles Moore platted the village of Carthagena, and mulatto clergymen Sam Jones and Harrison Lee served as Underground Railroad conductors. By 1860, about 100 black and mixed-race families totaling 600 people owned more than 10,000 acres in the adjacent townships of Butler, Franklin, Granville, and Marion, where the settlement also built four Protestant churches, the earliest in 1841, and three schools. The black cemetery stands beside the cemetery of St. Aloysius Church, built by German Catholics in 1878, and the remaining sections of an ornate wrought iron fence mark the extent of the Catholic cemetery. Although the schools became integrated, the black churches closed in the 1930's. After U.S. Route 127 was widened in 1952, only 240 headstones remained, the last burial took place in 1957, and the Jennings family moved away in the 1950's, marking the end of the black settlement of Carthagena. Beginning in the 1970's, the Mercer County Genealogical Society recorded all information from the headstones and identified nine black and mulatto veterans, one from the War of 1812 and eight from the Civil War.