Known for most of its length as Sudlersville Road, the highway runs 13.55 miles (21.81 km) from MD 213 in Church Hill east through Sudlersville to the Delaware state line, where the highway continues as Delaware Route 300 (DE 300).

MD 300 forms part of an east–west connection between U.S. Route 301 (US 301) in northern Queen Anne's County and Dover, Delaware.

The highway heads east as two-lane undivided Sudlersville Road and crosses MD 19 (Main Street) before leaving the town.

[6] Queen Anne's County constructed with state aid two segments of 9-foot-wide (2.7 m) macadam road west from Sudlersville, both of which were widened to 15 feet (4.6 m) between 1924 and 1926.

[6] The county also constructed a state-aided concrete road from Main Street in Church Hill east to the west end of the second macadam section in 1919 and 1920.

[7] MD 300 from Sudlersville to the Delaware state line was constructed as a concrete road in four segments.

[16] The highway was extended west to its current terminus as part of the project to build the Church Hill bypass in 1969 and 1970.