Dexter is a city situated in Washtenaw County, Michigan, in the United States. As of the 2020 United States census, the city's population wa…Dexter is a city situated in Washtenaw County, Michigan, in the United States. As of the 2020 United States census, the city's population was recorded at 4,500. Originally established in 1830 as a village, Dexter was incorporated as a city on November 20, 2014. It is located next to several rivers and trails, including the Border-to-Border Trail. Within city limits are the Dexter Cider Mill, one of the oldest cider mills in the state of Michigan, as well as a farmers market and various other local businesses.