So if every US citizen of voting age is eligible to vote, why do we have to register to vote?

First, to establish that you are actually a citizen; second, to establish that you are eligible to vote (that you're at least 18 years old and not otherwise prohibited from voting--e.g., a felon in some states); third, to establish your residency to determine where and for which local offices you can vote; and finally, to help ensure that you only vote once.

You need to make an effort. And it enables prevention of voter fraud. Because not every citizen of voting age can vote.

If you do not register how do we verify you are a citizen? Do you also drop bread crumbs to find your way home from school? I hope you realize by asking a question like this on this site you have lost all credibility.

1) To ensure that a registered voter only votes once.

2) Various government jurisdictions are required by statute to notify voters how and where to vote. Voter registration is really the only way to ensure that this happens because you provide your mailing address.

For the simple reason to keep it orderly and to prevent CHEATING-------and making sure you only vote ONCE.............and don't go around to hundreds of polling stations, trying to load the vote.

because states and counties require you to be a resident to vote there. you also cannot vote in another state or county.

To make sure that no one votes twice.

To make sure each person votes only once.

Not everybody in the US is a citizen