Established May 11, 1861
Reuben Shipley, William Wyatt, Abiathar Newton and George Bethers formally established the cemetery on May 11,1861 on two acres of land donated by Reuben Shipley, which he divided off from the northwest corner of his 80-acre farm.
In 1853, Reuben Shipley, a Black slave and overseer of a large plantation in Missouri, agreed to drive a team of oxen to Oregon with the Robert Shipley family, in exchange for his freedom. After arriving in Benton County, Oregon, Reuben worked on the farm of Eldrige Hartless, a neighboring pioneer of the Plymouth community, who was part Black. Reuben saved $1,500 and bought 80 acres adjoining the Shipley's farm. Reuben married Mary Janes Holmes, a slave of Col. Nathaniel Ford, who brought his family and slaves to Oregon in 1844, and purchased the settlement of Rickreall. Slaves were not legal in Oregon and court cases are recorded about this family. Reuben purchased Mary Jane's freedom for $700. This is believed to be the first case of a slave being sold in Oregon as property.
Together Reuben and Mary Jane built a cabin similar to those in the southern states. The cabin was a local landmark for many years with its huge fireplace and quaint proch shaded by a huge locust tree, which had been brought to Oregon by immigrants. They raised a family of three boys and three girls. the family participated in the social life of the Plymouth community and was well liked. They were the only Black family in Benton County.
In 1861, Reuben Shipley donated 2 acres of his farm for the establishment of the cemetery on the condition that Black people could be buried there. The name given to the cemetery was chosen to show unity with the anti-slavery Northern forces during the Civil War. Abiathar and Norrie Newton had donation land claims just north and west of the cemetery and during the first few years there were many Newtons burried there, leading some to start calling it the "Newton Cemetery."
Reuben died in 1873 and both he and his wife, Mary Jane, some of their children, and Mary Jane's second husband, Alfred Drake, are buried in Mt. Union Cemetery.
Long after Reuben died, the Shipley farm was owned by the Wheeler family who built a large home on the farm. Mrs. Minnie Gray Wheeler later sold more acreage to the Cemetery Association to meet the growing needs of the cemetery. That purchase brought Mount Union Cemetery it to its present size of 6.7 acres.