Unrelated to the Baltimore–Annapolis Boulevard, the commission constructed a wide macadam road from Glen Burnie to Brooklyn, which was then in Anne Arundel County, in 1915. In Brooklyn, the new highway connected with the south end of the Light Street Bridge that crossed the Patapsco River into Baltimore. With a road completed from Annapolis to Baltimore, the roads commission suggested that it should not be required to complete a road between Glen Burnie and South Baltimore. The commission asked the Maryland General Assembly to pass a bill releasing the commission from the responsibility of completing the highway from Glen Burnie to South Baltimore. However, the Maryland General Assembly disagreed with the Maryland State Roads Commission and passed a bill in 1914 requiring the commission to finish the boulevard between Glen Burnie and South Baltimore. The Baltimore–Annapolis Boulevard north from Glen Burnie to Baltimore was finished in 1916. The final gap in the Baltimore–Annapolis Boulevard was filled when the first modern Severn River Bridge was completed in 1924. This concrete bridge, which had a roadway width of and a steel bascule draw with a horizontal clearance of , replaced a narrow one-lane bridge. The entire length of the Baltimore–Annapolis Boulevard was widened to with a pair of wide concrete shoulders by 1927. The highway's bridge over Marley Creek was rebuilt from a width of to in 1926.