This train is ready to board
inbound passengers for the longest
possible of the four
Green Line terminal pairings, Lechmere out to Riverside. Trains on
that branch now
normally terminate not here, but under downtown, at Government Center.
The antecedents of today's Green Line were once numbered trolley routes.
The extensive system shrank over several decades, and the present
lettering scheme for the various branches came about in 1967.