Delaware County is a county located in the U.S. state of Oklahoma. As of the 2020 census, the population was 40,397. Its county seat is Jay. The county was named for the Delaware Indians, who had established a village in the area prior to the Cherokees being assigned to relocate to Indian Territory in the 1830s. Delaware County was created in 1907. Prior to becoming Delaware County, a large portion of the area was known as the Delaware District of the Cherokee Nation. Today, Delaware County continues to be recognized by the Cherokee Nation as the Delaware District.

Jay is a city and county seat of Delaware County, Oklahoma, United States. The population was 2,448 at the 2010 census, compared to 2,482 at the 2000 census, a decrease of 1.4 percent. Almost 40% of its residents are Native American, thus Jay is home to numerous Cherokee tribal offices and a health clinic for the Delaware District of the Cherokee Nation. Jay has a council-manager system of government. Becki Farley is the mayor with Kyle Stump serving as Vice Mayor.