Topo maps have long been friends of all explorers and wanderers. Contours of the land make or break your journey, but this critical relief is not captured by the satellite images or street maps usually found on Google Earth. Togographical maps however do show relief. Topo maps typically display the gradient of the land as concentric contour lines which can be easily followed. Topo maps also label structures, buildings, railways, and other features of interest to someone trying to navigate on their own power. All continental areas of the US have been mapped in topographic detail and these crisply printed topo maps are available inexpensively from the United States Geological Survey.

But this is the age of freeconomics, so there are two ways to acquire topo maps for free.

The easiest way 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.

Topographical Overlay layer in Google Earth.

However there is another way to print free topos. 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.

Once prepared, you can then print the topo map out yourself if you have a wide color printer. But since you can order the topo map itself for only $6 (plus postage) from the same government website, why not buy if you have the time?

There are four good reasons you might want to download and print your own topo maps.

1) It is instant. When you need a topo today, it’s worth the hassle of messing with files.
2) It is selective. Way too often the spot you are looking for is in the corner of 4 maps, which means you have to order all four just to center the chosen area. You can eliminate 3 extra maps by combining the parts you want into one map.
3) You can print it on Teslin map paper (see below) which holds up in field use.
4) It can be lots cheaper.

However most of us don’t have extra wide printers. You can print a series of cropped portions of a topo on regular 8.5 x 11 sheets at the official scale, but I wouldn’t want to do many by hand like that — say a long trail. (Someone should write a utility for that job; write me if you know of one.) Even a slightly wider printer which can handle a 11 x 17 size sheet (Ledger) will give you very usable results. I recently printed a river run by cutting out the relevant sections of 6 topos, then printing each sheet at standard scale on an 11 x 17 page. We got served wonderfully.

Teslin +ink-jet map, printed on both sides. No-see-through when used horizontally.

Whatever size you print, you can drastically increase the usability of your home-printed map by upgrading to Teslin paper. National Geographic sells cut sheets of Teslin as Adventure Paper. Think tyvek, but smoother and printable. It’s available in boxes of 25, 15 or 10 sheets depending on size. You send this this untearable, nearly indestructible paper through your ordinary ink jet printer. The resulting map (see picture above) can then be dunked in the ocean, folded again and again, and it won’t break. When applied as if the paper were Glossy Photo Paper, your typical ink jet ink seems to adhere well and hold up pretty good to abuse. It can be printed on both sides, too, to further compact your maps.

-- KK 08/4/08