This place was named by William Roberts, pioneer settler. He is said to have lived in the Rogue River country and also in the Klamath country as early as 1865. He selected the word Dairy because he had previously lived in a community by that name in an eastern state. The post office of Dairy was first established May 8, 1876, with Roberts postmaster. Dairy Siding was about a mile northeast of the community. The valley in which Dairy is situated was at one time known as Alkali Valley, but now bears its Klamath name, Yonna Valley.