In 1947, the newly formed Metropolitan Transit Authority (M.T.A.) decided to build to Lynn as a rapid transit line, and construction began in October 1948. The first part of the Revere Extension opened to Orient Heights on January 5, 1952, with intermediate stations at and Day Square. The station was the terminus of the line until April 21, 1952, when station opened. Until September 1972, some trains terminated at Orient Heights rather than to provide more frequent service on the inner part of the line.