I know that the U.S. has seemingly favored vertical integration of rockets, while the USSR has favored horizontal integration (and raising them for launch) of rockets. Of course, horizontal integration presents its own problems the larger the rocket gets, though the N1 being lifted to a vertical position does indicate to me that it can be done.
So, how do you get the U.S. to mainly use horizontal integration of launch vehicles, and the USSR to favor vertical integration of launch vehicles instead?