At a four-way stop where two vehicles arrive at the same time, who has the right of way?

When two vehicles arrive at a four-way stop at the same time, the driver on the right has the right of way. If they arrive at different times, the first to stop goes first. If three or four vehicles arrive simultaneously, the standard rule is still 'yield to the right', though in practice drivers often resolve the situation by eye contact and one driver waving the other through. Right-of-way rules are 'yielding' rules: they tell you who must wait, not who absolutely must go. A driver who legally has right of way should still yield when needed to prevent a crash. Vehicles going straight typically have right of way over those turning left at signal-less intersections, but the same-arrival-time rule still defers to the right.