Archaeological studies have shown that at least three different periods of prehistoric people had lived in the area covered by Delaware County.

[3] Few Native Americans lived in the area until the early nineteenth century, when the federal government began relocating tribes from the Eastern United States.

In 1828, the Western Cherokee moved from Arkansas Territory into the area just south of the present Delaware County.

In 1832, the Seneca moved from Ohio into an area that included the northeastern part of Delaware County.

This group founded the town of Jay, where they built a wooden courthouse and won an election to move the county seat.

There are no oil, gas or mineral resources of economic consequence, but the county has abundant water.

[3] Lake Eucha, a man-made reservoir on Spavinaw Creek, completed in 1952, lies primarily within Delaware County.

Said counties combined are the third-largest tourism destination in the state, following only the Oklahoma City and Tulsa metropolitan areas.

[12] The following sites are in Delaware County are listed on the National Register of Historic Places: