Dewey County is a county in the western part of the U.S. state of Oklahoma. As of the 2020 census, the population was 4,484. Its county seat is Taloga. The county was created in 1891 as "County D". In an 1898 election, county voters chose the name Dewey, honoring Admiral George Dewey.

The Territory of Oklahoma was an organized incorporated territory of the United States that existed from May 2, 1890, until November 16, 1907, when it was joined with the Indian Territory under a new constitution and admitted to the Union as the state of Oklahoma.