In 1860, S. Augustus Mitchell took over his father’s business, issuing an atlas which included a map of the new state of Oregon and the Washington Territory. Up to 1859, Oregon Territory had run from the Pacific Ocean to the Continental Divide, but when it was made a state, the eastern border was stopped at approximately the 117th meridian, with what had been the eastern part of the territory attached to Washington, giving that territory an inverted “L” shape. This is one of the few maps to show that configuration, which lasted only until 1863, and this example is an early one, where the territory to the east of Washington is labeled as “Nebraska.” In 1861, the area to the east of Washington became “Dacotah” territory and Mitchell changed the map appropriately.
Also of particular interest is the indicate of the “Emigrant Route from the States,” that is, the Oregon Trail. It is clearly marked running from the South Pass, through Fort Boisee, and then to the Columbia River at Walla Walla. The western parts of both Oregon and Washington are broken into counties, with towns, forts and rivers indicated. In the western parts, some settlements and forts are indicated, but mostly it is rivers and lakes and mountains depicted. A fascinating picture of the American Northwest early in its development.