In 1898, after the retirement of their father, Frederick Law Olmsted, Sr., Frederick Law Olmsted, Jr. and his half-brother, John Charles Olmsted, formed the Olmsted Brothers firm. Significant firm projects include the1906 Lewis & Clarke Exposition in Portland, OR and 1909 Alaska-Yukon-Pacific Exposition in Seattle. The pair terminated the firm's involvement in the 1915 San Diego Exposition rather than despoil the natural landscape of Balboa Park with planned structures.