For those of you searching for Willis N. Tiffany in NY, I found him on the 1820 census for Greenbush, Rensselaer, NY
https://familysearch.org/pal:/MM9.3.1/TH-1951-25143-39554-82... His name is badly transcribed on the index and IGI but the individuals in the household match with a wife and two young sons. It's also interesting that his first name is spelled Wyllys instead of Willis so that may give some clue as to a possible family connection.