The Detroit Department of Transportation (DDOT) is the primary public transportation operator serving Detroit, Michigan. In existence since 1922, DDOT is a division of the city government, headed by a director appointed by the mayor. Primarily serving Detroit and its enclaves, DDOT is supplemented by suburban service from the Suburban Mobility Authority for Regional Transportation (SMART). In 2023, the system had a ridership of 11,048,700, or about 38,900 per weekday as of the fourth quarter of 2023.

The Suburban Mobility Authority for Regional Transportation (SMART) is the public transit operator serving the suburbs of Detroit, Michigan, United States. Beginning operations in 1967 as the Southeastern Michigan Transportation Authority (SEMTA), the agency was reorganized and renamed SMART in 1989. SMART operates 44 bus routes, plus paratransit and microtransit services.