With the renumbering, Route 3 was rerouted onto the Southeast Expressway (I-93) into downtown, Route 3A was truncated to its current end in Neponset (although it is technically concurrent with Route 3 between Boston and Burlington), and the former alignment of Routes 3 and 3A were redesignated as Route 203. While the former routes had been signed north–south, the new route was signed east–west to better reflect its actual direction of travel.
