Caro is a city in and the county seat of Tuscola County, Michigan, United States. The population was 4,145 at the 2000 census, at which time it was a village. The 2008 census estimate places the population at 4,020. Caro is located northeast of Flint and east of Saginaw in Michigan's Thumb region. It is the largest community in the Thumb, both by population and by area; it is an industrial and commercial center for the region as well.