The Colonial was a service of the Pennsylvania Railroad and New York, New Haven and Hartford Railroad between Union Station in Washington, DC and South Station in Boston, Massachusetts. It was operated until 1973 by Amtrak.
The Colonial existed by 1935 as a service of the Pennsylvania Railroad and New York, New Haven and Hartford Railroad between Washington, DC and Boston. The PRR merged into Penn Central Transportation in 1968, which absorbed the NYNH&H in 1969. When Amtrak began operations on May 1, 1971, it took over the Colonial, which ran as trains 170 and 171 (changed to 173 and 174 in the November 14 timetable). Its last trip was made on April 28, 1973.