Map basics
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USGS 3DEP elevation data, explained
What the USGS 3D Elevation Program collects, the elevation models it publishes, and how that data becomes the contour lines on a topo gift.
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What contour lines mean (and how to read them on a topo map gift)
Contour lines join points of equal elevation. Here is how to read spacing, intervals and shapes, so a topo design on a mug or print makes sense at a glance.
See the full collection of Midwest topo map gifts on CafePress.