- Brooklyn : George McKibbin & Son 1949
- 8vo.
- cloth.
- 30 pages.
- Order Nr. 111
- Price: $ 10.00

First edition, limited to 1000 sets. Wheat, the well-known California historian, undertook this work in an effort to trace the opening of the American West by studying the succession of maps which, beginning in the 1540s, accurately trace the paths of the explorers and the record of the resulting growth of knowledge.
He sought out every map, relating to the Transmississippi West before 1861 and selected the most interesting and important. These maps cover the story of Spanish, French and English exploration.
In all, 1,302 maps are fully described, with many illustrated in full-page. A chronological calendar of maps, a full index, and a system of marginal references make these volumes easier to use than any other comparable work.
This set lacks volume III which covered the period 1846-1854.