Route 106 is a 34.31-mile-long (55.22 km) west–east highway in southeastern Massachusetts, United States. Its western terminus is at Route 1A in Plainville and its eastern terminus is at Route 3A in Kingston. Along the way it intersects U.S. Route 1 in Plainville.

Route 1A is a north–south state highway in Massachusetts, United States. It is an alternate route to U.S. 1 with three signed sections and two unsigned sections where the highway is concurrent with its parent. Due to the reconfiguration of tunnel interchanges brought on by the completion of the Big Dig, Route 1A is discontinuous in the downtown Boston area. Vehicles entering Downtown Boston via the Sumner Tunnel must take I-93 north to the exit for Government Center and make a U-turn to access the entrance ramp to I-93 south and vice versa.