David Thompson (1770-1857) is considered by many to have been the most important surveyor of North America. His achievements - mapping the Saskatchewan River, the great bend of the Missouri River, the Great Lakes and the headwaters of the Mississippi as well as the Columbia watershed - are the stuff of legend. Late in life Thompson wrote a retrospective memoir of his explorations, but the best way to understand his years in the fur trade is by reading his journals. With the publication of David Thompson's Columbia Journals Barbara Belyea makes this possible. Documenting the Northwest Company's efforts to find trade routes across the Canadian Rocky Mountains, Columbia Journals also reveals Thompson's personal interest in mapping the great river of the West sought by generations of explorers. His accounts provide a detailed picture of the fur business and remind us to what extent the territory he explored has been transformed by settlement, roads, and hydroelectric dams. Thompson's journals trace the fur trade's westernmost expansion while his hand-drawn maps preserve a contemporary image of the country he explored. The extensive notes that accompany the Columbia Journals provide a documentary context for Thompson's own account. Details of Thompson's manuscript maps are included, as is the work of other cartographers of the period. By placing Thompson's work in the context of the fur-trade and comparing his accomplishments with those of his contemporaries, Belyea shows what makes David Thompson truly remarkable and worthy of attention two hundred years after his surveys of the Columbia River.