Where did William Hopper's birth date of 31 Mar 1782 and place of birth Rensselaer Co. NY come from?
William HOOPER, son of William HOOPER and Eunice Leonard was baptized in Schaghticoke Reformed Dutch Church in Rensselaer Co., NY - no baptismal date or witnesses were given but his birth date was recorded as 31 Mar 1782 - the same date you sight in your entry. Wm. and Eunice also had Isaac b. 5 Jan 1779 baptized there.

THe bad news is I have no unidentified Wm. Hopper b. bef 1762.
Maria (Ree) Pratt Hopper
compiler of The Hopper Family Genealogy;
Descendants of Andries Willemszen Hoppe(n)
of New Amsterdam 1651-1658; First Six Generations See www.reetree.com