The movements to and from the Francis Scott Key Bridge to the south were made via MD 158 to the west before it collapsed from being struck by a ship in 2024.

[4] At Bread and Cheese Creek, northbound MD 151 crosses to the east side of I-695, which runs in the median of the state highway.

[1][3] MD 151 enters the city of Baltimore just west of its intersection with Rolling Mill Road and Kane Street.

The state highway passes under I-95, Norfolk Southern Railway's Bayview Yard, and Amtrak's Northeast Corridor railroad line.

At North Point Road, MD 151's name changes to Erdman Avenue and the highway veers west to pass under CSX's Philadelphia Subdivision railroad line.

MD 151 continues northwest concurrent with US 40 Truck as a six-lane boulevard between the Armistead Gardens neighborhood to the east and industrial facilities on the west.

The state highway passes by Archbishop Curley High School and through the Belair-Edison neighborhood before reaching its northern terminus at US 1 (Belair Road), onto which US 40 Truck turns west.

Erdman Avenue continues northwest as a two-lane undivided street along the eastern edge of Clifton Park to MD 147 (Harford Road).

MD 151 was reconstructed and extended north as a four-lane divided highway from Sparrows Point to Wise Avenue in Dundalk between 1940 and 1942.

[13] In Baltimore, Erdman Avenue was expanded to a divided highway from US 1 to US 40 and extended south to North Point Road by 1942; MD 151's underpasses of the Baltimore and Ohio Railroad (now CSX) and Pennsylvania Railroad (now Amtrak) and its interchange with US 40 were completed at that time.