Colorado will be voting a week ahead of the other 49 states this year.
Election day in the other states is November 8th, the first Tuesday after the first Monday of November.
In Colorado, thanks to a change in the state constitution in 1992, Colorado votes on the first Tuesday in November. Most years that will coincide with the national vote, but not this year.
Election officials say they are working to make sure everybody knows when to turn up at the polls.