SR 644 has no intersections in the 0.41-mile (0.66 km) it covers in Carroll County,[1] just passing by a blend of woods and fields.

The rural setting the highway traverses is a blend of woods and fields, with a few homes dotting the landscape.

The route bends northeast, then north again, as it passes by the hamlet of Millport, where it meets SR 518 at its western terminus.

Next, the route bends to the west briefly, then resumes a northwesterly trek, and comes upon a split intersection with McKaig Road.

SR 644 bends north, turns northwesterly, then begins to trend to the west as it approaches Mechanicstown Road.