#Utah is being fairly slow in counting its ballots this year. Since my spouse is working as a ballot counter, I have a little bit of understanding why - though please keep in mind this is like third-hand information.
First, you need to know that most of Utah votes by mail-in ballot - over 90% of ballots were cast this way in 2024 (though the legislature has passed a law that makes changes to this in the future).
Second, there was a law passed by the state legislature last year that will require voters to write the last 4 digits of their SSN or drivers' license number on mail-in ballots, in addition to their signature (which has always been required.)
BUT the law is not yet fully in effect; for now, writing those 4 digits is optional, though the text on the printed ballots makes it sound like it is mandatory, so I assume most people are doing it. If you do write the digits, they must match what's on file - if you don't, your ballot gets processed anyway.
The normal process here for validating mail-in ballots is to have machines do *most* of the signature verification, with ones "challenged" by the machines reviewed by trained humans, as well as spot checks to verify the machines' accuracy.
However, the machines are not capable of validating those last-4-digits.
So, this year, every single signature, plus the digits, are being validated by humans (including my spouse).
Despite the fact that they (at least Salt Lake County) have been checking signatures for weeks, since many ballots come in early, it's simply taking too long to validate all the ballots that came in on election day.