18 wheelers are allowed in tandem in some states...is North Carolina one? How about Kentucky?
Utah and Idaho allow triples. I've seen way too many of those triples whipping like a long snake at over 80 MPH.
There's no state that allows multiple 53' trailers. If you're thinking of pups, that's different. I think both KY and NC limit pup length to 28', with no overall limit.