Similar to a Moving Road-Block, a Mormon Road-Block is the situation where three or more vehicles are pacing each other on the freeway. This causes problems for those trying to speed past slower vehicles. A Mormon Road-Block is worse than a Moving Road-Block because Mormons typically drive mini-vans, Suburbans, or specially made 15 person vans, so as to carry their families. This means that even if vehicles are not trying to pace one another, a roadblock can still occur because of the simple size of the vehicles.
Tim: Why weren't you here on time? Didn't you leave early enough?
Mike: I left in time, but I got stuck behind a Mormon Road-block