I didn't know it was a Michigan thing until I moved to San Francisco. Then I learned California has their own weird traffic ways, but not the same as ours.
On many roads where there is a median of some sort and you can't make a direct left turn it's designed so that you have to go past the street you want to turn left on and they have a "turn around" as we call it and you make a U turn (thus getting to the other side of the median) and then as Blue said you have to come back to the road you wanted to turn left on and turn right, thus you actually made a left turn. So simple, you see? :boggles:
Now there is the "turn right" to go left thing, too. Is that regional? You know, you turn right and then get all the way over to the left and enter the "turn around" and then you end up going left.
Many intersections have both. I prefer the go right to go left myself.
And then there is the Florida "turn at your own risk and hope for the best" left turn area. We never did quite figure it out when we were there on vacation only to find out my sister who has lived there quite a few years said she doesn't understand it either, she just does what everybody else does and that is to make your own rules.