- Your Ad Here Onondaga County is a county located in the U.S. state of New York. The estimated population for 2016 is 466,194. The county seat is Syracuse. Sponsored Links History Onondaga County was formed in 1794. The name Onondaga derives from the name of the Native American people who lived here, who called themselves Onoda'gega, sometimes spelled Onontakeka. The word means "People of the Hills." Sometimes the term was Onondagaono ("The People of the Hills"). Haudenosaunee (Iroquois) people continue to reside in a separate nation within Onondaga County. |