I 15 Thru Salt lake City?

Not a Clue wrote:
We came through SLC twice end of May and first part of June. Coming from the North we came through SLC about 9am on a Friday, it was busy but no problem and good traffic flow.

Traffic flow is not the problem. It flows only too well. The problem is trying to change lanes when other drivers seem determined not to let you. :W

OTOH, if you're used to driving in SoCal, it probably doesn't bother you at all. :D