In 1799, Cayuga County was formed from Onondaga County, thereby decreasing the size of Onondaga County by more than one-half.
In 1808, the southern portion of Onondaga County was taken for Cortland County.
In 1816, Oswego County was formed from the northern section of Onondaga County and a portion of Oneida County.
In 1828, Onondaga and Cayuga Counties exchanged land, thereby establishing the current-day Onondaga County boundaries.
28 June 1998
24 October 1999
This Web Page was created by Kim Branagan
-[an error occurred while processing this directive]- person to view the this page since 2 July 1998