The three consecutive walk-offs tie a franchise mark set by the 1988 Expos, who did it against the Cubs and the Cardinals over a three-day span in late July that year.
The Nationals are the second team to string together three in a row this season. The Rays accomplished the feat in late May with a win over the A's and a pair over the Red Sox. The Phillies and Rangers both did it 2013.
The 1986 Astros hold the record for consecutive walk-off wins with five, which included three straight over the Expos.
Jamie Ross is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.