The Southside Connector was a proposed expressway that would connect the Bourne Bridge to the Mid-Cape Highway near exit 59 on Cape Cod. Currently, a similar route is served by two two-lane highways, Sandwich Road and a stretch of US 6, on opposite sides of the Cape Cod Canal. Originally, the expressway was planned to be routed north of the canal. Plans were changed when it was discovered that the Sagamore Bridge was overcrowded and the nearby Bourne Bridge was under capacity. The route was shifted in the 1970s and the current plans of the route would go through the northern half of the Massachusetts Military Reservation.