The bulk of the collection documents William Emory's service on the Mexican boundary survey in the years 1848 to 1858. Series I contains correspondence with members of the boundary commission, the American and Mexican Survey parties, and government officials. Correspondence for 1849-50 describes California during the Gold Rush and Forty-Niners on the Gila route. There are also other military records. Series II contains letters and other records from Emory's service in Kansas and in the Civil War.