Regina, It is not so much the date that matters as it is the interior design. If you go to our website you will be able to see some photos of the inside of the barn. The one that shows the anchorbeams and tenon are the ones that will tell you immediately if it is a NWDB or not. True form Dutch barns seem to stop being built in the 1840's. There are some transitional barns built after that date up until the 1870's. We will be doing a NWDB seminar sometime in the spring at the Herkimer County Historical Society for prospective barn documenters. If you are interested let us know and we will put you on the announcement list. I will forward your information about the barns in the Catskills to Hudson Valley Vernacular Architecture Society and they can check them out. Thank you for the information. Our survey is somewhat like the art style called pointillism, every little dot adds to the picture. Rolland Miner