[6][7] Delaware County is included in the Columbus, Ohio, metropolitan area.

U.S. President Rutherford B. Hayes was born and raised in Delaware County.

The area including Delaware County was once home to numerous Native American tribes.

In 1804, Colonel Moses Byxbe and Henry Baldwin, among others, migrated to central Ohio from Berkshire County, Massachusetts, and built a town on the west bank of the Olentangy River.

[8] On February 10, 1808, the Ohio government authorized the creation of Delaware County.

Ohio Wesleyan University, a liberal arts college, was founded by Methodists in 1842.

Delaware County had Northern sympathies during the Civil War, and abolitionists brought the Underground Railroad through the area.

The Civil War played an important part in Delaware County's growth, bringing railroad business and technology.

[citation needed] As of the 2010 United States census, there were 174,214 people, 62,760 households, and 47,977 families living in the county.

[29] The only Democratic presidential candidate to win the county from 1856 to the present day was Woodrow Wilson in his 1912 and 1916 electoral victories.

However, in 2020, Joe Biden came within single digits of flipping the county, the closest result since Lyndon Johnson's landslide victory in 1964.

The growth of suburban Columbus, which has been growing increasingly Democratic in recent years, is one of the factors driving Delaware County away from its former overwhelming Republican support.

[31] In November 2023, the county voted for Issue 1, which amended the state constitution to guarantee a woman's reproductive rights, by a margin of 59.21%-40.79%.

The airport contains a 5,000-foot (1,500 m) runway, flight terminal, lounges, and weather briefing areas.

Additional local print publications include ThisWeek Delaware News, which covers the city of Delaware and the villages of Galena and Sunbury; and ThisWeek Olentangy Valley News, which covers Powell and the Olentangy Local School District.

Both weekly papers are among 21 published by ThisWeek Community News, headquartered in southern Delaware County.

Other local publications include the Transcript, the student paper at Ohio Wesleyan University.