Westchester County public service trailblazer Herman Geist has died at 100.

Geist became as the first-ever chairman of the Westchester County Board of Legislators after serving as a lieutenant in World War II.

He also co-founded the Westchester Parks Foundation, served as a board trustee for the Westchester Medical Center, and chaired the Westchester County Bicentennial Commission.

A cause of death was not immediately known as of Saturday night.