1850
An act of the Wisconsin legislature was passed regarding the Oak Hill Cemetery Association.
The regionGrade A · 1 independent source
The evidence
“Patrick's. The Oak Hill Cemetery Association was organized January 8, 1851, under an act of the Wisconsin legislature passed in 1850. The management of the association is in the hands of nine trustees, and the lot owners are the stockholders.”
1908-brown-rock-county/26-history-of-janesville.md, Vol. 2, PDF p. 86 / book p. 597
Brown, William Fiske, editor. Rock County, Wisconsin: A New History of Its Cities, Villages, Towns, Citizens and Varied Interests, from the Earliest Times, Up to Date. Chicago: C. F. Cooper & Co., 1908. 2 vols. archive.org/details/rockcountywiscon01brow, archive.org/details/rockcountywiscon02brow.
Grade A: Found on a page of one of our sources