John Potter Cook and Chauncey Ferris, his friend, were the third and fourth men to come to Hillsdale. They proved to be the "movers and shakers" for the community during their entire lifetime. These two men, at the age of 20, left their home in Cato, New York to journey to the west with a wagonload of mercantile goods. They stopped first in the small settlement of Jonesville and established the first store. However, by 1834 they decided that Hillsdale offered them more opportunities. In 1838 they set up the first grist mill using the mill pond race as it merged with the St. Joseph River. It was a simple mill using only a millstone and a water wheel to furnish power but from 1838, a mill on this same site has continued to operate to the present time. (The mill was purchased by F.W. Stock in 1869 and was operated by that same family for more than 80 years.)
One humorous note concerning Cook was, that as the settlement evolved into a village, he was designated as the wrestler to test any newcomer to the area.
Together, Ferris and Cook platted much of the settlement which became Hillsdale. These two men, with foresight knew development would be enhanced with a railroad connection. Cook, becoming a contractor for Michigan Southern Railroad, and working with Henry Waldron and Charles T. Mitchell (two more of the early settlers), was able to extend the railroad from Adrian in Lenewee County, where it had ended, to Hillsdale. Recognizing the benefit, the men then erected warehouses along the terminus in Hillsdale in order that products might be shipped from the area.
By being instrumental in organizing Hillsdale as a county in 1835, Cook was appointed Treasurer and Ferris became the County Clerk. Ferris also was elected supervisor and served as a school commissioner and as mayor of Hillsdale. Appointed by President Martin Van Buren, Cook became Hillsdale's first Postmaster. The two men were also given the task of building the first frame Court House.
Additionally, Cook served in 1845 in the State Legislature and then in the State Senate. He also was elected to two state Constitutional Conventions in 1850 and 1870 when Michigan framed its State Constitution
With his friends, Waldron, Mitchell and Ferris, Cook organized the first bank in the village and then in 1874 established the Hillsdale Savings Bank
Cook labored for his community tirelessly as a member of the Hillsdale Board of Education and the Board of Trustees of Hillsdale College when it was moved from Spring Arbor ion 1844. Through Cook's efforts the Hillsdale County Fair was organized and Cook served as its first Tresurer.
Hillsdale was well served by the work and the promotion throughout their lives by John Potter Cook and Chauncey Ferris.