The first convention of the Republican Party was held in Jackson, MI (July 6, 1854) but the party's birthplace was in Ripon, Wisconsin (March 20, 1854). https://en.wikipedia.org/wiki/Republican_Party_(United_States)
Fun quiz - having lots of cousins in Michigan paid off, and it is my husband's birthplace which helped. too. (He still talks about touring the Kellogg's factory in first grade, watching them roll out corn flakes.)