Identification requirements vary among states. Some states do not require ID documents at the polls at all, but rely on a matching signature instead.
To find out your state’s identification requirements, go to the State Voting Requirements directory, input your state, and look under the Identification Requirements tab. Underneath this tab there is a sub-header with information regarding Voting In-Person.
The U.S. Vote Foundation recommends that, if you have one, you bring a valid, photo-ID with you to the polls.