One. There is no national marriage registry, and the record you want is at a county clerk’s office, and it costs about nine dollars.

Nobody checks.

The licence application asks whether you have been married before and how it ended, and the answer is taken on trust, and in most states there is no mechanism by which it could be anything else.

Which means that a marriage certificate proves a ceremony happened.

It does not prove that anybody was free to be at it.

If you want to know whether a person is divorced, you do not look for a divorce.