Located east of Mount Union Avenue approximately one-quarter of a mile north from the intersection of Bellfountain Road and Plymouth Road. The cemetery is situated on the eastern slope of the hill with views to the north, south, and east. An unusual event took place in the year 1861 when this cemetery was established by Reuben Shipley, an early black pioneer of Benton County, who donated two acres of land on the condition that black people could be buried there. The cemetery property was deeded to Benton County in 1861 and officially platted in 1879. Reuben Shipley came to Oregon in the 1850's with the Shipley family in exchange for his freedom. Eldridge Hartless, a neighboring pioneer of the Plymouth community, employed Reuben Shipley on his farm. Reuben saved $1,500 and purchased eighty acres of land, part of which is the Mount Union Cemetery. The cemetery now has 6.7 acres. In 1857, Reuben Shipley married Mary Jane Holmes after purchasing her freedom for $700. This is believed to be the last case of a slave being sold in Oregon as property. Together, they built a cabin, farmed, and raised six children. The family fully participated in the social life of the Plymouth community. Reuben and Mary Jane Shipley are buried in this cemetery, as well as Mary Jane's second husband and some of her children. Abiathar and Rachel Newton had Donation Land Claims just to the north and west of the cemetery, and during the first few years there were many Newtons buried here. During the 1920's and 1930's some called this the Newton Cemetery. Grave rows run north and south. Most of the tombstones and inscriptions face west, with the stones placed at the west end of the grave. Older sections are recognizable but new and old burials are intermixed. Scattered shrubs and grasses are interspersed among the graves, along with several big-leaf maples.