It's a big day in America as millions of people vote to choose who they want to run for President in November.
Super Tuesday is the most important day in the primary elections, which is when voters pick which candidate they want to represent their party.
Twenty-four states are all voting today, which is more than any other single day in the campaign.
The results are expected to reveal the winner for the Republicans. Democrats may have to wait a bit longer.
That's because the race between Democrat candidates Hillary Clinton and Barack Obama is really close.
They'll probably have to wait for the results of the 20 other states who haven't voted yet to see who'll run for President.
The main candidates for the Republicans are John McCain and Mitt Romney, although Mike Huckabee and Ron Paul are still campaigning for votes.