Free topographical maps

Kevin Kelly @ Cool Tools:

The easiest way [to obtain free topo map data] is to download a free nifty app for Google Earth, called the Topographical Overlay, that will add a KMZ "layer" of official US topo maps on Google Earth. Once installed you can toggle it on or off. When on, the Topo Overlay displays the standard 7.5 minute topos as one seamless map of the country. This makes it very easy to center your interest in the middle of your custom map. (You can buy a similar service on a not-cheap set of CDs from National Geographic, but you get the same thing here for free.) For browsing, this arrangement is hard to beat. You can zoom in, or out, and scroll forever. Its major drawback is printing. I have not been able to get the displayed map to print larger than one half of a standard letter page.

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...You can download, for free, a high resolution PDF file of any US topo map made. These are the same maps that the Google Earth app is using, but here they are dished out one by one in PDF format. Go to the USGS Map Locator page, and search for the quad you want. You can type in an "street" address just like in Google. Click on the appropriate miniature map and then choose which scale map of the area you want to download. The PDF files of the standard 7.5 minute topo map will be between 6 and 16 megs. You'll need Photoshop or equivalent to crop and size them. Be prepared to use some heavy duty processing power. These are big, very detailed maps.