By the time you're reading this, Green Line trains will be journeying along five brand new stations. That's right, it's finally opening day for the Green Line Extension.

ICYMI, the Union Square Station opened in March. Now, the remaining stations — East Somerville, Gilman Square, Magoun Square, Ball Square, and Medford/Tufts — are ready for passengers.

Why is this a big deal?

The project has been planned for three full decades, has a price tag of $2.3 billion, and will lead to an estimated 50,000+ train trips per day.

The City of Somerville summed up just how much work has gone into this effort:

"After decades of advocacy, a lawsuit, endless planning, delays, a miraculous win of federal funding, more advocacy, an 11th hour save via a $50 million payment, bridge closures, travel disruptions, and several years of less-than-welcome construction impacts, the Green Line Extension is finally here."

What's different?

Get ready for a brand new sound. Frank Oglesby, who has been the voice of the MBTA since 1997, is being replaced with a text-to-speech service on all train lines.

Plus, payment looks a bit different at these new stations. Here's a look at how to validate your fare before hopping on board.

How can I mark the occassion?

There will be plenty of pomp and circumstance at two community events hosted in Somerville.

🗓️ Opening Day Celebration | Monday, Dec. 12 | 7-8 a.m. | Ball Square Station | Perhaps you were on the historic first ride at 4:45 a.m. If not, you can still stop by to chat with Mayor Katjana Ballantyne and fellow commuters + grab opening day memorabilia.

🗓️ Go Green Line! Community Celebration | Saturday, Dec. 17 | 2-4 p.m. | Somerville High School, 81 Highland Ave. | Enjoy live music, a children's choo-choo train, a food truck, hot cocoa, and the opportunity to participate in an oral history project.

Plus, there will be an MBTA ribbon-cutting ceremony at the Medford/Tufts station at 10 a.m.