The Massachusetts Bay Transportation Authority will launch late-night bus, subway and streetcar service beginning in the spring, Gov. Deval Patrick announced.
Patrick said $20 million was available from state funding and corporate pledges to backstop the pilot program for Greater Boston's transportation system.
Late-night service, said Patrick, could boost the region's economy and provide affordable transportation options to employees working late-evening shifts.
Beginning next year, service on all subway lines, light rail and the 15 key bus routes will run until 3 a.m. on Friday and Saturdays. Expanded service will not include commuter trains or ferries.
"My hope is that this will be a popular option for enough customers that we can institute it permanently in the future," said Richard Davey, secretary and chief executive of the state Department of Transportation, which oversees the MBTA.
During the pilot program, fares will remain at the same level as those during regular service, although transit officials could adjust late-hour fare prices further down the road.