# Hayden Geological Survey of 1871

> 1871 federal geological exploration of US territories

**Wikidata**: [Q5686314](https://www.wikidata.org/wiki/Q5686314)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/Hayden_Geological_Survey_of_1871)  
**Source**: https://4ort.xyz/entity/hayden-geological-survey-of-1871