Route of the U.S. Geological Fortieth Parallel Survey (1867-1872)

The points on the map represent locations along the route of the U.S. Geological Fortieth Parallel Survey (1867-1872). Click on a point, and then click on the thumbnail image to view Robert Ridgway’s correspondence he wrote in that location.

Points along the route:

1. June 24, 1867 - Sacramento, California Camp 1

2. August 11, 1867 - Big Bend, Truckee, Nevada Camp 12

3. September 1, 1867 - Banks of Humboldt River Camp 17

4. October 15, 1867 - Buena Vista, Nevada Camp 19

5. January 14, 1868 - Carson City, Nevada

6. August 1868 - Ft. Ruby, Nevada

7. June 14, 1869 - Salt Lake City, Utah

To view more, visit the Ridgway Brothers: Explorers, Scientists, and Illustrators digital history collection