M-3 is a north–south state trunkline highway in the Detroit metropolitan area of the US state of Michigan. For most of its length, the trunkline is known as Gratiot Avenue (/ˈɡræʃɪt/, GRASH-it). The trunkline starts in Downtown Detroit and runs through the city in a northeasterly direction along one of Detroit's five major avenues. The highway passes several historic landmarks and through a historic district. It also connects residential neighborhoods on the city's east side with suburbs in Macomb County and downtown.