It was opened in 2019 and travels 12.5 miles (20.1 km) along Airport Way and State Route 527, connecting 32 stations in the cities of Everett, Mill Creek, and Bothell.

[2]: 59  A study was partially funded by the state legislature in 2012 and was prepared by Parsons Brinckerhoff, determining that the project would cost $42–48 million to construct and attract 3,300 riders when it opened.

[5] During the 2015 session of the Washington State Legislature, Community Transit was granted the authority to increase sales taxes to fund operation of Swift II, pending voter approval via a ballot measure;[6] the Washington State Department of Transportation also gave $6.8 million in funding to build the line's northern terminus at Seaway Transit Center.

[10] An additional $6.8 million grant from the Washington State Department of Transportation was used to build the line's northern terminus at Seaway Transit Center.

[18] The Green Line serves 34 stations, grouped into 18 pairs with two terminals, in the cities of Everett, Mill Creek, and Bothell.

[19] Each station has a raised platform for level boarding, ticket vending machines, ORCA card readers, and real-time arrivals information.