Been working on the Washington County, NY Harshas (see this link for the progenitor). As I've told Marjorie, I've found James and some of his children, and a bunch of people from 1840 on, but the pieces I can identify in-between don't link up well. There's a John born 1784 who is claimed as the father of a Daniel, born 1796! (I know Harshaws are precocious, but I'm not convinced of that.) Unfortunately, there's lots of Johns and James and Davids around and because the census shows only the household head's name before 1850, it's hard to link them together.
What's interesting is the more you search, the better you can become at it. I'm finding the Rootsweb.com searches to be helpful--most people seem to track just their line back. If you're lucky you can get 2 or 3 lines meeting at one ancestor.