​Free Topographical Maps for your Garmin Handheld GPS

Idaho Parks and Recreation Map

It references ALL Idaho public trails. You can create a track and print a map but not download GPX.
Colorado Trail Explorer

U.S. GEOLOGICAL SURVEY

​by USGS
​USGS Topographical Maps: These classic "Topo" maps are free and printable but not editable. They are in a GeoPDF format. Read the "How to ?" instructions at the top of the web page.​The terrago plugin for Adobe Reader allows the user to learn about the amazing properties of GeoPDF maps.
​The Avenza Mapping App lets you use GeoPDF for GPS purposes but is not free. Better to avoid this product and use CalTopo.

NATIONAL FORESTS

​​​​​​US Forest Service "USFS" Maps
​These are the best if you are in a national forrest
The Avenza Mapping App will open geo-enabled PDF

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Forest Service Interactive Map
Concise identification of trail numbers​

NATIONAL PARKS

​National Park Maps

Glacier National Park​

Grand Teton National Park

Yellowstone National Park

REI Guide to
​National Parks

WILDERNESS
Click on a wilderness and then click on read more to find out regulations.

​A "GIS" geographic information system shows information
on maps. Here is a good example from Wilderness Connect

Frank Church River of No Return Wilderness

Bridger Wilderness
​

Major State and National Trails

Continental Divide Trail

Nez Perce National Historic Trail
Great Western Trail

Other Public Places

City of Rocks and Castle Rocks, Idaho

​​Campgrounds, monuments, byways, recreation areas, rental cabins, wild and scenic rivers, state parks, wildlife management areas, wildlife refuges, National trails

​Geologic Map of Idaho
Still looking for maps like these for Wyoming and Montana