Motorcycle trips and backpacking were my favorite vacations for thirty years. On those trips I almost always carried a Huntsman. Awhile back I traveled by car for 4 consecutive months. During that trip I had only three knives with me the entire time, Victorinox Spartan & Classic and a Buck 110. Don't remember needing anything else. Extensive travel for me includes; opening cans, food prep, occasional fires, personal grooming etc.
So if I had to limit my knife selection to only one knife for a cross country trip a Victorinox Evo 18 would be my first choice.
Legal everywhere (I know of) in the USA, pocket and people friendly with a good selection of stainless steel tools. Probably the most qualified to meet all the needs I've experienced during previous travels.
Show here with a Puukko because I like them.

And any future cross country trip I might find myself on will likely be by auto and a larger fixed blade does make that type of travel a bit easier.
edit to add; all this travel talk is sparking a bit of wander lust in me... might have to make some plans soon