[2][3] Subsequent land-based exploration by Alexander Mackenzie and the Lewis and Clark Expedition and development of the fur trade in the region strengthened the competing claims of Great Britain and the United States.

[4] The competing interests of the two foremost claimants were addressed in the Treaty of 1818, which sanctioned a "joint occupation", by British and Americans, of a vast "Oregon Country" (as the American side called it) that comprised the present-day U.S. states of Oregon, Washington, and Idaho, parts of Montana and Wyoming, and the portion of what is now the Canadian province of British Columbia south of the parallel 54°40′ north.

[7] At that time, the only governments that existed in the Oregon Country were the individual local Native Americans communities, as no one nation held dominion over the territory.

[8] These earliest documented discussions, mostly concerning forming a government, were held in an early pioneer and Native American encampment and later town known as Champoeg, Oregon.

[9] The two-chamber Oregon Territorial Legislature was responsible for passing laws, with seats in both the upper-chamber council and lower-chamber house of representatives filled by local elections held each year.

[11] In addition, a poll tax of 50 cents for every qualified voter under age 60 was assessed and a graduated schedule of merchants' licenses established, ranging from the peddlar's rate of $10 per year to a $60 annual fee on firms with more than $20,000 of capital.

[15] In 1850, 10 years after the end of the Second Great Awakening (1790–1840), of the 9 churches with regular services in the Oregon Territory, 5 were Catholic, 1 was Baptist, 1 was Congregational, 1 was Methodist, and 1 was Presbyterian.