Another very valuable tool is to get copies of topographic maps of the area. If you get the township, and section number from the older maps, you can easily transfer that to new maps using the same section numbers. Usually, there aren't many differences from the older maps to new ones. Topozone.com can show you maps of the area with hills, valleys, and water located on them. Many fields are shown also. Using the older maps and the new ones, you can typically get the exact location of an old farm line. I've done this several times and had good luck with it. It takes some time to learn to read all out of the topo maps, but they are very useful. Once you get the right location, make sure to use the 1:25,000 scale for the best resolution. Bruce