A native of New Hampshire, he immigrated to the Oregon Country in 1837 to work at the Methodist Mission, and there would participate in the Champoeg Meetings.

[1][3] Willson was recruited to work at the Methodist Mission founded by the Reverend Jason Lee in the Willamette Valley as a layperson.

[1] He traveled by ship on the brig Diana, where he was instructed informally in medical training by Dr. Elijah White during the voyage.

[1][2] On May 18, 1837, Willson and other recruits for the Methodist Mission arrived in what was known as the Oregon Country, a region whose control was under dispute primarily between Great Britain and the United States.

[1] Willson participated in the Oregon Exchange Company in 1849 that minted the Beaver Coins prior to the arrival of U.S. authority in the region.