Navigate the Past

The USGS has been mapping the same ground over and over since the 1880s, and every printing survives as a scan. Navigate the Past puts all of them in one stack, oldest at the bottom, and hands you a GPS so you can go and stand on a trail that stopped being drawn in 1957. EVERY PRINTING, NOT JUST AN OLD MAP Pick a spot and the timeline shows one tick per printing, in lanes by series: 7.5 minute, 15 minute, 1:100,000 and 1:250,000. Some quadrangles have fifteen printings between 1900 and 1975. Drag across the lane and they run as a flipbook, so the contours hold still while everything people built moves. A PRINTING IS NOT A SURVEY The card tells you which. "Printed 1959 from the 1954 plate, 5 years on. Nothing here was checked in the field after 1954." That is the difference between a trail that existed in 1959 and one that existed in 1954 and was still being reprinted for another decade.…