Mechanicsville is an unincorporated community and census-designated place in the southern part of the town of Thompson in Windham County, Connecticut, United States. It is bordered to the north by North Grosvenordale and to the south by Putnam. Connecticut Route 12 runs the length of the community, along the east side of the French River. Mechanicsville was first listed as a CDP prior to the 2020 census.