> I'm curious about how this works in practice. If you're a tourist visiting the US during a vote can you just show up to a voting polling station and cast a vote? If you don't have to show your ID what happens from the time you walk up to a polling station until you cast your vote and walk out again?

In most states, you must be registered to vote before election day. In those states, non-citizens who attempt to vote will be asked their name and address before they are handed a ballot. When they are found to not be on the registration list for that polling precinct, they will not get a regular ballot. They may be given the chance to cast a provisional ballot, but it will be thrown out during the counting process when evidence cannot be found that the person was eligible to vote.

The voter registration process has proven to be a highly effective means of preventing ineligible voters from voting. The exceptions tend to be when different government departments fail to communicate effectively to catch people registering in multiple places, or ineligible criminals attempting to register. Voter ID does not meaningfully improve the security against non-citizens voting.