In 1948, William F. Callahan, commissioner of the Massachusetts Department of Public Works (MassDPW), proposed an expressway to connect Logan International Airport with downtown Boston. Anticipating increased traffic loads, he proposed that the East Boston Expressway be constructed in conjunction with a second two-lane tunnel to supplement the existing two-lane Sumner Tunnel.
The Master Highway Plan for the Boston Metropolitan Area released that year described the need for the East Boston Expressway as follows:
Two major desire lines of vehicular traffic terminate in the East Boston-Revere area. The volumes indicated are much lighter than on any other expressway section in the Boston Metropolitan Area. It is also noted that movements are relatively short between termini. Presently, the existing two-lane Sumner Tunnel, connecting inadequate through routes with Logan Airport and MA 1A to the northeast, serves this traffic. This facility is now overtaxed primarily because it is being used traffic being detoured from other less desirable routes. Present plans contemplate the immediate improvement of connections from the existing tunnel to Logan Airport and the northeast. This improved facility, known as "East Boston Elevated Highway," is designed to connect the Sumner Tunnel with the airport, and to provide a high-speed expressway through East Boston to connect with the existing four-lane semi-expressway to the North Shore. The 1.2-mile-long elevated expressway, which was expected to carry 30,000 vehicles per day (AADT), was estimated to cost $8.5 million.
Almost immediately, the MassDPW embarked on constructing the East Boston Expressway. Stretching about one mile from the portals for the Sumner and Callahan tunnels, the six-lane expressway immediately rises above the streets of East Boston, and furnishes access to and from Logan Airport before touching down at McClellan Highway (MA 1A), a four-lane arterial highway.
Completed in 1951, the East Boston route was the first expressway completed within the city of Boston. Originally designated C-1, the expressway received the MA 1A designation in the late 1970's. (The route may have been designated US 1 for an interim period in the mid-1970's.) In 1977, the MassDPW reconstructed elevated sections of the expressway. Despite the reconstruction, like most early expressways, the East Boston Expressway remains characterized by design flaws such as sharp curves, a lack of shoulders, and inadequate acceleration-deceleration lanes.