Thank you both for these answers. I've looked at the references given. What I was looking for was a little more detail about what the various plat indications are on the map cited in the profile given so I could pin down my great grandfather's actual lot but I can do that, more or less, with the town. I did reread the information at Ancestry about the U.S. Historic Land Ownership Atlases because, initially, it was unclear exactly how much of the country was surveyed. Doing a search on that title, took me to a Wikipedia article which has a lot of detail. That article took me to an article about the Public Land Survey System which also has a lot of interesting information and any more would be above my head. Having read or tried to read the plat survey information at the county office of one of my ancestor's lots was also an education as it uses the metes and bounds surveying system which is, in my opinion, ridiculous as almost all of the reference point of the survey are moveable and removeable. In any case, I would have to visit the county of town offices to ask questions about the historic land map and I assume that the plats have changed somewhat over time. There are so many political and historic ramifications in this one little topic it makes my head spin. I'm going to close this question. Thank you.