Somerville and Medford will soon have at least seven new T stations, thanks to the MBTA's Green Line Extension. The project – which extends the Green Line past Lechmere Station – consists of two new branches terminating in Union Square and at Tufts University. The first three stations are set to open in 2017.
However, it won't be the first time the cities will have light rail access. Streetcar lines actually extended from Boston into its surrounding towns in the early 20th century, until they were replaced by today's bus lines. In fact, if you know where to look, you can still see some old rails peeking through the pavement.
The MBTA's history is full of extensions, replacements, and closed lines (the A Line, anyone?). Thanks to vanshnookenraggen.com, you can view an animated map of the MBTA's history in a single gif.