RI line in Sheldonville to Wrentham.
Extension of RI 121. 121 was part of modern MA 133 between Essex and Gloucester in 1930. It may have reached north to Ipswich. Between 1959 and 1961, this route was renumbered to be part of 133.
Modern 121 was part of MA 11 in 1933. It was renumbered to 121 between 1961 and 1966.
121 is also listed on MassHighway’s traffic count page as the connection between MA 125 and NH 121 in Haverhill. However, this is not an official route.