Prologue to Lewis and Clark: The Mackay and Evans Expedition

Wood investigates the Spanish-sponsored Mackay-Evans expedition of 1795-1797, which ascended the Missouri River to the Mandan villages and produced maps and geographic intelligence that proved invaluable to Lewis and Clark’s planning. James Mackay and John Thomas Evans, traveling under Spanish auspices to counter British influence on the upper Missouri, compiled detailed observations of the river, its tributaries, and the Native nations along its banks. The article documents how Lewis obtained copies of the Mackay-Evans maps and journals in St. Louis before departure, and how these materials shaped the expedition’s route planning and diplomatic strategy. Wood demonstrates that the Lewis and Clark Expedition did not venture into completely unknown territory but rather built upon a foundation of prior European and American exploration that has often been overlooked in popular narratives.