From WMATA:
“Between Friday, Dec. 20 and Monday, Dec. 30, Metro will alter train service and close some downtown stations as part of a major construction project to improve tracks and signaling, which will result in a smoother ride for customers. During this period, free shuttle buses will replace trains in between affected stations. Shuttles will use the existing bus lanes on H and I streets to speed travel.
Dec. 20-26: Farragut West, McPherson Square, and the lower level (Blue, Orange, Silver service) at Metro Center will be closed.
Dec. 27-30: Farragut West, McPherson Square; lower level (Blue, Orange, Silver service) at Metro Center, Federal Triangle, and Smithsonian; and the lower level of L’Enfant Plaza (Blue, Orange, Silver service) will also be closed.
Dec. 31: All stations reopen.
Metro strategically picked these closure dates to minimize impacts to your travel. Typically, during this time of year, ridership is historically 40% lower. One longer closure also prevents months-worth of weekend shutdowns in the same area.”