Crossing State Lines with someone who is married could get you 3 years under the Fed Mann Act

just read this since i was curious about it, and honestly i don't see where it says that at all,
- however I do know you've going straight to jail if caught crossing state lines with a minor...
 
Where this is relevant is that if a group of young adults is pulled off a boxcar and you have some over 18 and some under 18 you could have a problem. I have seen older men hop trains with young girlfriends who are as young as 14. While that might be legal in Utah or West Virgina (as long as the relationship is not consummated) that would be a violation of the Federal Mann act