"Lake No Negros" is a perfectly sensible name for Lake Oswego, Oregon. Up until about 1963 Lake Oswego had enforced sunset laws, as in "black man, don't let the sun set on you".
Despite its current reputation as a liberal state, Oregon has a long history of institutionalized racism. Blacks were not allowed to own land and were discouraged from settling in Oregon. The KKK had a strong presence in the state, though most of their agitation was against Catholics and Native Americans. In the 1920s Oregon elected a Ku Klux Klan governor.