You Are Here

I’m reading You Are Here by Hiawatha Bray, a history of mapping.

I’ve always been fascinated how a 1940s era topographic map always matches up perfectly with a modern GPS in a cellphone – you can drive down the road and the map track is in the perfect location 80 years later. It’s a method called geometric triangulation. Nobody dreamed of a cellphone GPS in the 1940s. It’s amazing how truly accurate USGS Topographic Maps truly are.

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