The white supremacist, anti-Semitic, anti-Catholic organization known as the Ku Klux Klan established itself in Oregon in 1921, when Klan members from the southern United States came to recruit members. By 1923, Oregon Klan leaders claimed that the state had 35,000 members in over 60 chapters. Klan members won elections for local, county, and state offices in 1922, and the organization helped elect Democrat Walter M. Pierce as governor of Oregon. Klan members and their allies in the Oregon State Legislature passed bills prohibiting foreign-born residents from owning land and prohibiting public schools from using textbooks that criticized the founders of the United States. The Klan in Oregon also helped to pass an initiative mandating that all children from ages 8 to 16 attend public school, a measure meant to target Catholic schools; this measure was never implemented, and the U.S. Supreme Court ruled it unconstitutional in 1925. The number of Oregonians who were members of the Ku Klux Klan dwindled in the mid- and late 1920s, due both to displeasure with the leadership style of Exalted Cyclops Fred L. Gifford and multiple scandals involving the Klan in other states.

Source: "Ku Klux Klan," by Eckard Toy, Oregon Encyclopedia, https://www.oregonencyclopedia.org/articles/ku_klux_klan/