An MBTA SL1 bus emerges from the Silver Line tunnel at D Street in Boston’s Seaport District in 2007. The view behind the bus is today entirely obscured by private development. Photo by Connie | CC BY 2.0

What: Silver Line Tunnel Opens
Where: Boston
When: Dec. 31, 2004 

The last day of 2004 was the first day of the future for Boston’s newest neighborhood as the MBTA’s Silver Line SL1 and SL2 bus services launched. 

A ceremonial first bus sidled away from the platform at South Station and rolled through a dedicated tunnel under the Seaport’s streets built as part of the Big Dig and conceived during a surge in popularity of bus rapid transit systems around the world. Cheaper to construct than a train line, albeit offering lower passenger capacity and higher operating costs per passenger, “BRT” at the time offered a compelling vision of transit’s future.  

A final phase to connect Roxbury and the Seaport via a downtown tunnel fell victim to high costs estimates and the Great Recession. However, the existing system’s links to regional transit hubs like Logan Airport and South Station still helped catalyze nearly 10 million square feet of development in what was once acres of railroad yards made obsolete by changes in shipping technology – development that pays around 10 percent of the city’s property tax revenues. 

Today, the Silver Line has spawned an extension into Chelsea and carries tens of thousands of people from to jobs, shopping, homes, hotels and events in the Seaport and back again every day. The replacement of its ageing buses with a larger fleet of new vehicles is expected to add service in the years to come. 

“The Silver Line is an incredible engine for the Seaport’s present and the Seaport’s future…There’s no other area that has developed as quickly and attracted so many new employers and residents in such a short period of time.”
— Yannis Tsipis, WS Development 

To celebrate its 150th anniversary, Banker & Tradesman is highlighting significant moments in the history of Massachusetts’ real estate and banking industries. To suggest a topic, email

This Month in History: The Seaport Gets Its Transit Link

by James Sanna time to read: 1 min