In northern Berrien County, M-140 follows Watervliet Road to an interchange with Interstate 94 (I-94). The highway continues northward along Main Street into Watervliet, running through the middle of town and intersecting Red Arrow Highway, the former US 12. North of downtown, the trunkline curves through residential neighborhoods to the northeast around the east end of Paw Paw Lake. M-140 crosses into western Van Buren County about north of Watervliet. The highway crosses, and parallels, the Van Buren Trail in Covert. In South Haven Township, M-140 connects the South Haven Area Regional Airport with the I-196/US 31 freeway; north of this interchange, the highway continues as Business Loop I-196.