Tuscola County is a county in the Thumb region of the U.S. state of Michigan. As of the 2000 census, the population was 58,266. The county seat is Caro. The county was created by Michigan Law on April 1, 1840, from land in Sanilac County and attached to Saginaw County for administrative purposes. The Michigan Legislature passed an act on March 2, 1850, that empowered the county residents to organize governmental functions.