MD 173 begins at the entrance to Fort Smallwood Park northeast of Jacobsville.
The state highway heads south as Fort Smallwood Road, a two-lane undivided road that passes by several small beach communities on the Hog Neck peninsula.
After intersecting Bayside Beach Road, MD 173 turns southwest and passes along the northern edge of Jacobsville, where the highway meets the northern end of MD 607 (Hog Neck Road).
The state highway crosses Rock Creek and meets the northern end of Edwin Raynor Boulevard, where the highway turns north onto a four-lane road with a center left-turn lane.
MD 173 passes Northeast Senior High School in Riviera Beach before the highway reduces to a two-lane road with center turn lane at its intersection with Duvall Highway.

MD 173 continues north into Riviera Beach.
At its intersection with Riviera Drive and Bar Harbor Road, the state highway turns west and crosses Stony Creek on a drawbridge.
In Orchard Beach, MD 173 intersects the western end of its old alignment, MD 642 (Greenland Beach Road), then expands to a four-lane road with a center left-turn lane.
Passing Cox Creek, the state highway becomes a four-lane divided highway and passes the Herbert A. Wagner Generating Station and the adjacent Brandon Shores Generating Station.
MD 173 turns north at Solley Road and passes Marley Neck Boulevard before entering the city of Baltimore.
Upon entering the Hawkins Point area, the state highway meets Fort Armistead Road, which leads to Fort Armistead Park and an entrance ramp to eastbound I-695 (Baltimore Beltway).
MD 173 turns west and its name changes to Hawkins Point Road before the highway intersects Quarantine Road, which leads to a three-quarter diamond interchange with I-695.

MD 173 continues west as a four-lane undivided highway through the industrial area of Hawkins Point.
The state highway passes MD 172 (Arundel Cove Road) and then the access road to the U.S. Coast Guard Yard.
MD 173 crosses a CSX railroad line and expands to a divided highway.
The state highway, now named Pennington Avenue, passes under I-695 and then over Curtis Creek on a drawbridge.
 The state highway meets MD 710 (Ordnance Road) before reducing to an undivided highway and crossing Cabin Branch on twin bridges.
MD 173 intersects a CSX rail line at-grade and enters the neighborhood of Curtis Bay.
The northbound direction of MD 173 makes a pair of right-angle turns, east onto Birch Street and then north onto Curtis Avenue; the southbound direction uses Pennington Avenue through the neighborhood.
Curtis Avenue divides the residential and industrial portions of the neighborhood.
MD 173 meets MD 171 (Church Street) within Curtis Bay.
At the northern end of the neighborhood, the one-way pair ends and MD 173 turns west onto Patapsco Avenue to pass through Brooklyn as a four-lane undivided street.
The westbound highway has an entrance ramp to I-895 (Harbor Tunnel Thruway) immediately before reaching its northern terminus at MD 2 (Potee Street).
Patapsco Avenue continues as a municipal highway across the Patapsco River toward Southwest Baltimore.

MD 173 is part of the National Highway System as an intermodal connector between Quarantine Road in Hawkins Point and Patapsco Avenue in Curtis Bay.
The highway is also a National Highway System principal arterial from MD 607 in Jacobsville to Quarantine Road and from Patapsco Avenue to its northern terminus in Baltimore.
MD 173 begins at the entrance to Fort Smallwood Park northeast of Jacobsville. The state highway heads south as Fort Smallwood Road, a two-lane undivided road that passes by several small beach communities on the Hog Neck peninsula. After intersecting Bayside Beach Road, MD 173 turns southwest and passes along the northern edge of Jacobsville, where the highway meets the northern end of MD 607 (Hog Neck Road). The state highway crosses Rock Creek and meets the northern end of Edwin Raynor Boulevard, where the highway turns north onto a four-lane road with a center left-turn lane. MD 173 passes Northeast Senior High School in Riviera Beach before the highway reduces to a two-lane road with center turn lane at its intersection with Duvall Highway.
MD 173 continues north into Riviera Beach. At its intersection with Riviera Drive and Bar Harbor Road, the state highway turns west and crosses Stony Creek on a drawbridge. In Orchard Beach, MD 173 intersects the western end of its old alignment, MD 642 (Greenland Beach Road), then expands to a four-lane road with a center left-turn lane. Passing Cox Creek, the state highway becomes a four-lane divided highway and passes the Herbert A. Wagner Generating Station and the adjacent Brandon Shores Generating Station. MD 173 turns north at Solley Road and passes Marley Neck Boulevard before entering the city of Baltimore. Upon entering the Hawkins Point area, the state highway meets Fort Armistead Road, which leads to Fort Armistead Park and an entrance ramp to eastbound I-695 (Baltimore Beltway). MD 173 turns west and its name changes to Hawkins Point Road before the highway intersects Quarantine Road, which leads to a three-quarter diamond interchange with I-695.
MD 173 continues west as a four-lane undivided highway through the industrial area of Hawkins Point. The state highway passes MD 172 (Arundel Cove Road) and then the access road to the U.S. Coast Guard Yard. MD 173 crosses a CSX railroad line and expands to a divided highway. The state highway, now named Pennington Avenue, passes under I-695 and then over Curtis Creek on a drawbridge.  The state highway meets MD 710 (Ordnance Road) before reducing to an undivided highway and crossing Cabin Branch on twin bridges. MD 173 intersects a CSX rail line at-grade and enters the neighborhood of Curtis Bay. The northbound direction of MD 173 makes a pair of right-angle turns, east onto Birch Street and then north onto Curtis Avenue; the southbound direction uses Pennington Avenue through the neighborhood. Curtis Avenue divides the residential and industrial portions of the neighborhood. MD 173 meets MD 171 (Church Street) within Curtis Bay. At the northern end of the neighborhood, the one-way pair ends and MD 173 turns west onto Patapsco Avenue to pass through Brooklyn as a four-lane undivided street. The westbound highway has an entrance ramp to I-895 (Harbor Tunnel Thruway) immediately before reaching its northern terminus at MD 2 (Potee Street). Patapsco Avenue continues as a municipal highway across the Patapsco River toward Southwest Baltimore.
MD 173 is part of the National Highway System as an intermodal connector between Quarantine Road in Hawkins Point and Patapsco Avenue in Curtis Bay. The highway is also a National Highway System principal arterial from MD 607 in Jacobsville to Quarantine Road and from Patapsco Avenue to its northern terminus in Baltimore.
Maryland Route 173