A "through hiker" is defined in 58 Pa.Code 135.42 http://www.pacode.com/secure/data/05...5/s135.42.html for the purpose of identifying those who are allowed to camp in PA State Game Lands along the A.T. That differs significantly from the meaning of "thru-hiker". Nearly all "thru-hikers" are "through hikers," with the possible exception of these guys: http://appalachianloop.tumblr.com