Yes, Dec. 21 might be the shortest day of the year, but it is NOT the day with the earliest sunset in Northern Utah.
Thanks to being so far north, sunset actually now starts to get a little later every day from Dec. 8, until June here.
Sunrise on the other hand will keep getting later and later until about Jan. 8, 2012.
Then, it will turnaround.
But sunrise and sunset don't both automatically turnaround on Dec. 21. They have different rates.