The Detroit Department of Transportation (DDOT, pronounced DEE-dot) is the primary public transportation operator serving Detroit, Michigan. In existence since 1922, DDOT is a division of the city government, with headquarters in Midtown. Primarily serving Detroit and its enclaves, DDOT is supplemented by suburban service from the Suburban Mobility Authority for Regional Transportation (SMART). It is the largest transit agency in Michigan, with a ridership of 8,465,800 in 2021.