Over 75,000 people now live in Somerville's 4.25 square miles. The city is made up of a diverse group of individuals and neighborhoods. Tufts University straddles the Somerville-Medford line, and Harvard, MIT and Lesley University are all close by in neighboring Cambridge. As a result, students and professors are no strangers here. The population is otherwise a blue collar-white collar amalgam, with a healthy number of artists and urban hipsters also calling Somerville home. Gentrification and economic vitality increasingly define the Somerville of today. The emergence of Assembly Square is testament to this. Of vital importance to Somerville's future is the planned Green Line Extension. Once upon a time, Somerville was a streetcar suburb of Boston, with eight passenger rail stations. As it happens, seven new Green Line rapid transit stations are to be constructed in Somerville, starting with Union Square. Already highly walkable and bikeable, Somerville stands to become even less dependent on the automobile in future.