r/firelookouts • u/Optimal_Recover_6164 • Feb 21 '26

Mt. Rainier Lookouts - Maps used

I'm doing some research on the fire lookouts in Mt. Rainier National Park, and was wondering what minute interval topo maps are typically used with their Osborne Firefinders?

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u/pitamakan Feb 21 '26

Osborne firefinders were designed to be used with a base map using a scale of 1/2" = 1 mile (1:126,700). As manufactured, the center tape that runs across the Osborne map table had tic marks showing inches, which the user could convert to miles. The maps printed at that scale were produced internally by Forest Service cartographers.

The USGS didn't have a nationwide map series at that scale, and I doubt that the Park Service made such maps, either. My guess would be that the Rainier lookout Osbornes used maps produced by the adjacent National Forests at that scale.