Washington remains alive -- if only just -- in the hunt for a wild-card spot in the playoffs, trailing Columbus by four points with three games remaining.
Braden Holtby had 28 saves in the win as the Caps swept the two-game season series with St. Louis.
Maxim Lapierre scored for the Blues, who have lost three games in a row as they cling to a one-point lead over Anaheim for first place in the Western Conference, and a small lead over Colorado in the Central Division. Ryan Miller gave up four goals on 22 shots.
Notable deaths of 2014 [PHOTOS]
Michael Sam cut from the Dallas Cowboys