HathiTrust Digital Library, one of my favorite sources for digitized historical books, is also a great source for historical county atlases and other sources of historic landowner maps. A simple search for county atlas, for example, returns thousands of full-text results, including this 1914 Atlas of Wexford County, Michigan. You can also search by location and name of publisher, such as F. W. Beers, a popular map publisher of the mid to late 19th century, known for creating state and county atlases and maps of much of the northeastern United States.
Or use Google to search Internet Archive by restricting your search to return results only from that website. For some reason it often works better than searching the site directly! Try a search such as site:archive.org "county atlas" plus the name of your state or county of interest and see what turns up (the site:archive.org part of the search tells Google to return results only from that website). Without a locality name, my search returned over 2,800 results (I'm sure some were probably not relevant) from both the U.S. and Canada.
Google Books and FamilySearch Books have historical landowner maps as well. See what you can find!