When counties were established in New York in 1683, the present Onondaga County was part of Albany County. This enormous county included the northern part of New York State as well as all of the present State of Vermont and, in theory, extended westward to the Pacific Ocean. It was reduced in size on July 3, 1766, by the creation of Cumberland County, and further on March 16, 1770, by the creation of Gloucester County, both containing territory now in Vermont.