Most states' language is similar to California's 21801 which is must yield to vehicles "approaching frome the opposite direction which are close enough to constitute a hazard"
Not USA, but Ontario, CA actually does have this rule in 136.2[1]
Michigan found a 3rd option: If there are two cars going straight from one direction and one car waiting to turn left from the opposite, then it goes Straight, Left, Straight. This is regardless of the order that they arrive[2]
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I also find it absurd that this situation is not covered in every single States' driver's manual. After googling this, it's clearly contentious, and has been for years. If there ever was a situation that needed clarification it's this one.
I think it was New York's manual that had the section and had a list of questions "you should be able to answer" before proceeding (without answers provided). One of the questions was this situation, but I could not figure out the answer from reading the chapter!
1: https://www.ontario.ca/laws/statute/90h08#BK230
2: http://www.legislature.mi.gov/(S(did15hikprdseomawdqif0jc))/...
Utah law only talks about who must yield. I use to believe that a person going strait had the right of way. Some of the confusion may come from the wording from different ways of entering the roadway. In Utah it says the following.
41-6a-903 Yield right-of-way -- Vehicle turning left -- Entering or crossing highway other than from another roadway -- Merging lanes. (1) The operator of a vehicle: (a) intending to turn to the left shall yield the right-of-way to any vehicle approaching from the opposite direction which is so close to the turning vehicle as to constitute an immediate hazard;
This doesn't actually apply to a stop sign because it says "other than a roadway". It also talks about "opposite direction" and not cross traffic.
The other part of the law that actually seems to apply is the following.
41-6a-902 Right-of-way -- Stop or yield signals -- Yield -- Collisions at intersections or junctions of roadways -- Evidence. (b) After having stopped at a stop sign, the operator of a vehicle shall yield the right-of-way to any vehicle in the intersection or approaching on another roadway so closely as to constitute an immediate hazard.
https://le.utah.gov/xcode/Title41/Chapter6A/C41-6a-P9_180001...
Do you have a cite/link about this? I've heard people say different things, but I've never seen evidence that the left-turning vehicle has legal right-of-way in any state.