The longest primary U.S. Highway in Maryland is U.S. Route 40 (commonly abbreviated US 40) at 221.31 miles (356.16 km).

The shortest primary U.S. Highway in Maryland is US 11 at 12.83 miles (20.65 km).

The longest auxiliary U.S. Highway in Maryland is US 301 at 123.30 miles (198.43 km).

The shortest auxiliary U.S. Highway in Maryland is US 522 at 2.37 miles (3.81 km).

Highways; those five are shaded in dark gray in the list.