I don't know how it is in other parts of the country, but the states I have voted in Texas, Oklahoma, Indiana, Maryland, and Florida either didn't ask for my ID, or if they did it was a little old lady who didn't give two ####s about it. Would be very easy for any person to borrow another person's ID to vote. Now recently in Oklahoma they ask for your address, and they mark you off in a book to show you have already voted. This would work without an ID in a small state like Oklahoma, but I don't see how in the world they keep up with this issue in a large populated area.
If people were serious about this issue we would go to a standardized voting system that can be taught in high school, so that we don't have 1500 different ways to vote in different states, counties, and cities. We could use a fingerprint machine or some other high tech mechanism. But, it shouldn't cost the tax payer to vote.