Climbing Mt Katahdin

Thereís some confusion as to the exact height of Mt Katahdin. This sign at the summit says itís 5,267 feet; Charlie and Diane Wingerís book, Highpoint Adventures, lists the height as 5,268 feet; Wikipediaís figure is 5,269 feet; and the map I used during the climb shows the summit as being 5,271 feet above sea-level.