The museum was established on December 12, 1924, when the widow of Cornelius Earle Rumsey donated his collection of Native American artifacts to the City of Riverside.

Rumsey, a retired executive of the National Biscuit Company (Nabisco), came to Riverside for his health and subsequently developed an interest in Native American artifacts.

For many years, the museum shared its site with the city's police department, the U.S.D.A, and, during World War II, the Fourth Air Force.

The site and story of the Harada family embody local, state, national, and international issues of civil and individual rights, democracy, immigration, assimilation, citizenship, and diversity.

After his retirement from teaching at Riverside Junior College, noted naturalist Edmund C. Jaeger served as a curator for the museum and substantially enhanced the botanical collections.