Senator Hillary Clinton won the primary, but on the same day, her opponent Barack Obama secured enough delegate votes for the 2008 Democratic National Convention to ensure his eventual nomination for President by the Democratic Party.

South Dakota has 66 counties with 762 election precincts.

[3] Early on the day of the primary, hours before polls closed, the Associated Press projected Barack Obama's nomination for the presidency.

The projection was based on the declarations of a large number Democratic superdelegates, as well as exit polls of voters in South Dakota and Montana.

However, the AP calculated that Obama would be the Democratic nominee even if he lost the primaries in South Dakota and Montana.