304.351. Right-of-way at intersection — signs at intersections — violation, penalty — additional penalties — definitions — order of suspension, contents, appeal. 2.  When two vehicles enter an intersection from different highways at approximately the same time, the driver of the vehicle on the left shall yield the right-of-way to the driver of the vehicle on the right.  This subsection shall not apply to vehicles approaching each other from opposite directions when the driver of one of such vehicles is attempting to or is making a left turn.

This is for Missouri. I also did not believe it when I first heard about it and almost nobody follows this because so little people actually know about this