The son of Henry McAllister, one of Colorado Springs' most prominent citizens, Henry Jr. attended Swarthmore College and later earned a law degree. He became one of Colorado's most prominent attorneys and served for many years as the general counsel to the Denver and Rio Grande Western Railroad Company. The collection contains correspondence and records for McAllister's work with a number of firms, including the Grace Gold Mining and Milling Company, the Teutonic Consolidated Gold Mining Company, the Nellie V Mining Company, and the Trinchera Ranch Company.