M-90 is a state trunkline highway in The Thumb region of the US state of Michigan. It runs from near North Branch eastward to Lexington situated on Lake Huron. The highway is a lightly traveled roadway that runs through rural farmlands. The trunkline runs mostly east–west with two short north–south segments where it turns to run concurrently with other state highways. Along the routing, there are two river crossings and one railroad crossing.