The lookout structure was originally constructed on Johnstone Peak in Los Angeles County by the Angeles National Forest in 1939. A California Region 5 Plan BC-301 cabin on a 30 foot K-Brace steel tower.

Johnstone Peak was originally known as San Dimas Peak Lookout. The name was changed in June 1940 dedicated to the memory of W.A. Johnstone, pioneer conservationist who died in 1937.

The lookout cabin was dismantled and reconstructed at the Los Angeles County Fairplex in Pomona, California in 1992. The lookout is used as an interpretive site.

The Angeles National Forest Fire Lookout Association and Southern California Mountains Foundation Fire Lookout Program volunteers operate the lookout every year during the Los Angeles County Fair for visitors to experience the fire detection program.

Original location: 34.160096°N, -117.799767°W above San Dimas, California