Joppa Road has three main segments separated by very short breaks on its course through central and eastern Baltimore County.

The intersection is a short distance north of the expressway's interchange with the Baltimore Beltway that forms one junction between I-83 and I-695.

Joppa Road crosses over Roland Run and MTA Maryland's Baltimore Light RailLink and intersects Bellona Avenue, which leads to MD 139 (Charles Street) in both directions.

The two-lane highway crosses over MD 139 and meets the northern end of Charles Street Avenue.

Joppa Road enters the downtown area of Towson at its intersection with MD 45 Bypass (Bosley Avenue).

Joppa Road heads east from the circle as a four-lane undivided highway on the south side of the Towson Town Center shopping mall and on a bridge directly above part of the retail building on the south side of the road.

Joppa Road becomes undivided again as it approaches its intersection with MD 542 (Loch Raven Boulevard) on the northwestern edge of Parkville.

That state highway heads southwest through Rosedale to Baltimore and northeast toward Joppatowne, which lies near the site of the abandoned town of Joppa.

[1] Joppa Road is a part of the National Highway System as a principal arterial from Goucher Boulevard in Towson east to US 1 in Perry Hall.

[16] Between 1950 and 1952, the block of MD 148 immediately to the east of US 111 was shifted, widened, and reconstructed as a bridge over the ground floor of the first suburban location of the Hutzler's department store.

[23] The remainder of the highway was transferred from the state to county maintenance in 1963, the same year the Beltway opened from MD 542 to US 1.