At least 4-way stops have the same basic rules throughout the US (cars go in order of arrival).
2-way stops do not:
Consider the case where the first car to arrive is turning left, but cannot do so due to traffic on the main road. Then a car arrives from the opposite direction going straight. Who is supposed to go first? In some states it's the car that reached the stop sign first, in others it's the car going straight.
2-way stops do not:
Consider the case where the first car to arrive is turning left, but cannot do so due to traffic on the main road. Then a car arrives from the opposite direction going straight. Who is supposed to go first? In some states it's the car that reached the stop sign first, in others it's the car going straight.