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3. USGS Topo Maps

I don't know how many of you guys knew about this (probably everyone but me!), but the USGS recently began production of enhanced topo maps. They've currently mapped about half the states and are at varying degrees of completion with each. They've released each 7.5' x 7.5' quadrangle in PDF format using layers to show different types of data (added to this most recent release for the first time is a hydrographic layer!). You can turn on or off each type of layer with a simple toggle. The quadrangles are available for free download. I found they are each 10-20 MB in size. There is a toolbar you can also download (called TerraGo) that will enable you to interact with and personalize each map by marking spots, making notes, measuring distances and areas, and even track positions using your GPS. This seems like just the sort of tool a flyfisherman would find really useful. I'm pretty excited about it - Pennsylvania just got finished! Check it out here:

http://nationalmap.gov/ustopo/about.html#status

Thanks for this potentially valuable resource!