Montana territory Pacific Northwest Washington Oregon Idaho 1864 Mitchell mapMap of Oregon, Washington, Idaho, and Part of Montana. (Old Maps, 19th Century Maps, Americana, United States, Pacific Northwest, Washington, Oregon, Idaho, Seattle, Portland, Boise). Issued c. 1840, Philadelphia by S. Augustus Mitchell. (printed date is 1860, but this is clearly too early). There are many variant issues of this map, with differing borders and interior details. A comparison with other Mitchell maps of the 1860's 80's era will reveal