Known as Park Hall Road, the state highway runs 1.27 miles (2.04 km) from MD 5 east to MD 235 within Park Hall Estates in southern St. Mary's County.

MD 489 begins at an intersection with MD 5 (Point Lookout Road) in the unincorporated community of Park Hall Estates between St. Mary's City and Great Mills.

The state highway heads east as a two-lane undivided road through a mix of farmland and forest.

[1][2] MD 489 was assigned to Park Hall Road in 1956.

The entire route is in Park Hall Estates, St. Mary's County.