Many Years ago I flew into Portland and flew out of Eugene Oregon, And did a week long coast tour between the two citys. If I remeber correctly I shipped the empty box with some assembly tools to the next airport. I can't remember the carrier (its been 20 years) but I think it was either Greyhound bus or Fed Ex, or some cheap airline. It didn't cost that much since its based on weight. It was nice since I put together my bike in the airport and sent the box to the next desination. It was at baggage claim when I rode up to the airport in Eugene. There were a few new holes in the box but it was worth it not to have to deal with it.
Liam