About north of Acme, US 31 crosses into Antrim County as it runs between Elk Lake and the Grand Traverse Bay. Between towns, the landscape is mostly agricultural lands with mixed patches of forest. A few miles north of the county line, the trunkline passes through Elk Rapids and crosses a channel connecting the Spencer Bay portion of Elk Lake to Lake Michigan. North of this crossing, US 31 continues northeasterly, running on an isthmus between Torch Lake and Grand Traverse Bay. The highway passes through Eastport at the northern end of Torch Lake and intersects the western end of M-88. Further north, US 31 runs through Atwood and crosses into Charlevoix County.