Fall 1839
The Union school house was built by private subscription at the northeast corner of School and Prospect streets, Beloit.
BeloitGrade A · 1 independent source
The evidence
“At first this church received home missionary aid to the amount of $75, but thereafter became independent of aid. Meetings were held in private houses until the Union school house was built, by private subscription, in the fall of 1839, at the northeast corner of School and Prospect streets. In that house the Methodists and Episcopalians held services on alternate Sunday mornings,- and the Congregationalists every Sunday afternoon and evening.”
1908-brown-rock-county/13-beloit-churches.md, Vol. 1, PDF p. 287 / book p. 263
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