Because of its Red Line connection , Porter Square can serve as a temporary inbound terminus for the Fitchburg Line service when commuter rail service is disrupted between Porter and Boston 's North Station . It served this role during the 2004 Democratic National Convention , when North Station was closed for a week for security purposes , and during Green Line Extension construction in 2015 and 2017
2004 Democratic National Convention
2004 Democratic National Convention
Porter station