Known as Harford Road, the state highway runs 18.82 miles (30.29 km) from U.S. Route 1 (US 1) and US 40 Truck in Baltimore north to US 1 and US 1 Business in Benson.

Within the Mayfield neighborhood, MD 147 narrows to four lanes undivided and passes by Lake Montebello and through Herring Run Park, where the highway crosses the namesake stream.

Becoming undivided once again, MD 147 widens to accommodate two full-time parking lanes at Echodale Avenue before intersecting the southern end of Old Harford Road and then Northern Parkway in Hamilton.

The state highway widens once again to four lanes just before Putty Hill Avenue and meets Interstate 695 (Baltimore Beltway) at a cloverleaf interchange.

MD 147 crosses Long Green Creek and has a sharp S-curve around a hill before intersecting Glen Arm Road/Mt.

The state highway continues northeast and crosses Rocky Branch before its intersection with MD 152 (Fallston Road).

[2][3] MD 147 is a part of the National Highway System as a principal arterial from US 1 in Baltimore to Joppa Road in Carney.

[7][8] From North Avenue to the old city limits near Lake Montebello, Harford Road was reconstructed with a 50-foot (15 m) vitrified brick surface.

[13] Between 1936 and 1938, the tracks of a defunct interurban were removed and the space used to widen MD 147 to a width of 46 feet (14 m) from the Baltimore city line to Carney.