Thru-hikers need to resupply. That means hitching to town, or to a camp that has a store and other services.
Sometimes, it can take a while to get a hitch. You can improve your chances by doing a few simple things.
Be as neat as possible. Tuck your clothes in, wash your face, cover wild hair with a cap. Make the effort.
Don’t bunch with other hikers. More than two holding out thumbs at one spot is not wise–drivers will be reluctant to squeeze everyone in.
Pare off with a female, if possible. Your odds improve—I’ve seen it happen, and I’ll leave it at that.
Don’t look depressed or forlorn, especially if it’s a nice day. A driver would like to communicate and, perhaps, learn things. A driver is less likely to stop if he/she senses turbulence, or an attitude.