Starting in March or April 2014, the MBTA will start providing late-night subway and bus service until 3 a.m. on Saturday and Sunday.

Under the one-year pilot program, Red, Orange, Blue, Green and Silver Lines will stay open late on weekends. As will the 15 most popular bus routes.

BostInno reached out to the transit agency for confirmation about the exact bus routes that will provide late-night weekend service. In an email, MBTA spokesman Joe Pesaturo referred us to the 15 “key routes” labeled on the transit agency’s map. Those routes include:

1. 1
2. 15
3. 22
4. 23
5. 28
6. 32
7. 39
8. 57
9. 66
10. 71
11. 73
12. 77
13. 111
14. 116
15. 117

Routes 15, 23, 22, 28, 32, 39 serve just the City of Boston; Route 1 operates between Boston and Cambridge; The 57 extends from Boston into Newton and Watertown; The 66 serves Boston, Brookline and Cambridge; The 71 travels between Cambridge and Watertown; The 73, from Cambridge, Belmont and Watertown; The 77, between Arlington and Cambridge; The 111, from Boston to Chelsea, Revere and Everett; and the 116 and 117, from Boston to Chelsea and Revere.

To handle late-night service demands, Pesaturo told BostInno that the MBTA will be hiring more transit operators.

The MBTA has clearly made keeping the City open later a priority for neighboring communities, not just Boston residents. To illustrate this point, Annette Demchur, Transit Service Planning Manager, provided BostInno with the following daily ridership data for each key route:

• Route 1, Harvard Square – Dudley Station: 13,306
• Route 15, Fields Corner – Ruggles Station: 6,227
• Route 22, Ashmont – Ruggles Station via Talbot Ave. : 8,151
• Route 23, Ashmont – Ruggles Station via Washington St.: 11,867
• Route 28, Mattapan – Ruggles Station: 13,550
• Route 32, Cleary Square – Forest Hills Station: 10,130
• Route 39, Forest Hills – Back Bay Station: 15,018
• Route 57, Watertown Yard – Kenmore Station: 12,081
• Route 66, Harvard Square – Dudley Station via Brookline: 13,360
• Route 71, Watertown Square – Harvard Station: 5,488
• Route 73, Waverley Square – Harvard Station: 5,834
• Route 77, Arlington Heights – Harvard Station: 7,253
• Route 111, Woodlawn – Haymarket Station: 11,625
• Route 116, Wonderland – Maverick Station via Revere: 5,077
• Route 117, Wonderland – Maverick Station via Beach: 4,584

The 15 routes (see: left) were targeted in the MBTA’s Key Bus Route Improvement Program. The program’s goal was to reduce trip times, improve reliability, and make the system more cost-effective by redesigning each route.

A $10 million grant from the American Recovery and Reinvestment Act (ARRA) funded the transit agency project.

Construction began last spring and concluded in September.

For more detailed route information, please visit the MBTA website. Detailed descriptions of each route are available for download.