Is This Annoying Driving Habit An Exclusive Michigan Thing? Yes.
I've done unscientific research and I feel confident (and annoyed) in my findings.
left lane
Are You a Left Lane Driver? You’re About to Get Schooled by the Michigan State Police
A lot of people in Michigan are unaware that driving in the left lane is illegal. It's technically only supposed to be used as a "passing lane" and Michigan State Police are about to crack down on left-lane drivers.
Beginning March 1st through April, troopers are going to be on the lookout for those straddling the left lane; on all major freeways throughout the state...
For The Love Of God, Get Out Of The Left Lane!
Let me preface this by saying I'm not a patient person. I've been accused of having road rage once or twice. And I probably drive faster than most people, most of the time. But that doesn't make it any more acceptable for you to drive slow in the left lane...