The Red Line was the last of the four subway lines to be built.

Today, the Red Line runs from Cambridge to inner-city Boston.
 Important stops include Harvard Square Station; Kendall/MIT Station; Charles/Massachusetts General Hospital; and JFK/UMASS (the stop for the John F. Kennedy Presidential Library and Museum and the University of Massachusetts Boston.
 The Red Line intersects with the Commuter Rail, and with every other subway except the Blue Line.

The Red Line is the most used subway line on the MBTA.
 On average, about 74,450,000 people make trips on the Red Line every year.
The Red Line was the last of the four subway lines to be built.
Today, the Red Line runs from Cambridge to inner-city Boston.  Important stops include Harvard Square Station; Kendall/MIT Station; Charles/Massachusetts General Hospital; and JFK/UMASS (the stop for the John F. Kennedy Presidential Library and Museum and the University of Massachusetts Boston.  The Red Line intersects with the Commuter Rail, and with every other subway except the Blue Line.
The Red Line is the most used subway line on the MBTA.  On average, about 74,450,000 people make trips on the Red Line every year.
Massachusetts Bay Transportation Authority