A map of the Western United States showing the settlement of the US-Canada border by the Oregon Treaty of 1846, but pre-dating the cession of Upper California after the Mexican American War. This map was drafted while the War was still ongoing and is therefore vague about the ownership of Upper California. The United States had claimed ownership of California as early as July 1846 after the battle of Monterey, and the Californians had themselves capitulated in January 1847, but the subject was not formally decided until the Treaty of Guadalupe-Hidalgo was signed in February 1848.

The names of the resident Native American groups are the dominant feature on this map as there only a handful of American forts and settlements noted in the Oregon Territory. Spanish settlements in California are limited to a series of towns and missions along the coast from San Diego to San Francisco, as well as the inland settlement of Nueva Helvetia near modern-day Sacramento. The route of the Oregon trail from the Rocky Mountains to Oregon City is also marked on the map. An inset shows the route of the Columbia River from the Cascades to the Pacific Ocean in greater detail. Interestingly, this map pre-dates the incorporation of Portland as a separate town, making Oregon City the dominant settlement in the area.

Printed colour. [USA9814]