With polls closing in the Washington DC Democratic primary - the final primary of the season - presumptive presidential nominee Hillary Clinton is the projected winner of the district.
With 1% reporting, Clinton leads 81.1% to Sanders' 18.7%.
Clinton was declared the presumptive nominee last Monday, ahead of major primaries in New Jersey and California, having earned the 2,383 delegates needed to clinch the nomination.
She will not be officially declared the winner until the Democratic convention in July.
Rival Vermont Senator Bernie Sanders has vowed to remain in the race until superdelegates cast their official ballots at the convention.