The accessible station has a single island platform for the Red Line, as well as a dedicated busway on the surface.

The station has a single underground island platform, oriented approximately east-west under Davis Square.

Inbound buses on routes that do not terminate at Davis do not use the busway; they instead stop on surface streets near the station entrances.

[8] In January 1876, William Robinson installed one of the first test applications of his track circuit signaling system on the line between Elm Street and North Avenue.

[10]: 280  The streetcar and railroad service stimulated substantial development in the 1870s and 1880s as Davis Square quickly grew into an active commercial center.

[19] The city proposed to eliminate the grade crossings on the line, including the pair of College Avenue and Holland Street at Davis Square, in the early 1900s.

[28] On April 24, 1927, passenger service was rerouted over the rebuilt line; North Cambridge, West Somerville, and Somervile Highlands stations were closed.

[29] Although residents were opposed to the closures, the B&M wished to avoid the grade crossings on the line, which had seen 70 crashes in the past six years.

[34] In 1935, the city requested that the line be grade-separated as part of a Works Progress Administration-funded grade crossing elimination program.

[36][37][38] In the 1970s, local officials and citizen groups successfully petitioned the Massachusetts Bay Transportation Authority to create a Red Line subway stop in Somerville at Davis Square.

[39][4] Davis and Porter were the first MBTA subway stations made accessible during initial construction, rather than by renovation.