Early survey map of Washington Territory, conducted under the supervision of James Tilton, Surveyor General.
The Willamette Meridian from Portland to Puget Sound and the 4th Standard Parallel extending west to Gray's Harbor have been surveyed but much of the rest of the cartographical information is speculative at best. However, Wheat notes that the map is important in showing the Hudson's Bay Company's posts at Fort Okinakane and Fort Colville, along with the location of Lake Chelan, east of the Cascades. The US. Military Road from Ft. Steilacoom to Walla Walla is shown. The road proceeds from Seattle, up the White River, across Naches Pass and down to Fort Walla Walla, by the valley of the Yakama River.
This is the first edition of the map to show the Columbia River route for the Northern Pacific Railroad in the southeast, crossing over an unnamed pass south of Snoqualmie Pass and proceeding down the Yakama River. Curiously, no surveys had been made or were yet contemplated through this region.
The General Land Office (GLO) refers to the independent agency in the United States that was in charge of public domain lands. Created in 1812, it assumed the responsibilities for public domain lands from the United States Department of the Treasury. The Treasury had overseen the survey of the Northwest Territory, but as more area was added to the United States, a new agency was necessary to survey the new lands.
Eventually, the GLO would be responsible for the surveying, platting, and sale of the majority of the land west of the Mississippi, with the exception of Texas. When the Secretary of the Interior was created in 1849, the GLO was placed under its authority. Until the creation of the Forest Service in 1905, the GLO also managed forest lands that had been removed from public domain. In additional to managing the fees and sales of land, the GLO produced maps and plans of the areas and plots they surveyed. In 1946, the GLO merged with the United States Grazing Service to become the Bureau of Land Management.