There are 10 US Post Offices in Delaware County serving a total of 171,840 residents equating to 17,184 residents per post office. It's estimated that approximately 274,276 packages are handled across the 10 county post offices annually. Delaware County is a county in the U.S. state of Ohio. As of the 2010 census, the population was 174,214. Its county seat is Delaware. The county was formed in 1808 from Franklin County, Ohio. Both the county and its seat are named after the Delaware Indian tribe. Delaware County is included in the Columbus, OH Metropolitan Statistical Area. U. S. President Rutherford B. Hayes was born and grew up in Delaware County. It is also home to the Columbus Zoo and Aquarium."