The Norman B. Leventhal Map and Education Center at the Boston Public Library has a digital map library that researchers need to use when conducting family history. There are over 10,000 digital images of historic maps available to you from the comfort of your home. The access is free, and no registration is required.
If you are in the Boston area you can visit the Boston Public Library and use the Leventhal resources on the first floor of the McKim building. Onsite researchers have access to over 200,000 maps and 5,000 atlases.
The scope of the Leventhal map collection is international in area. Using the search term Canada West brings up almost one hundred examples. Maps using the search terms Prussia, Scotland, and Switzerland are available. There are a lot more country maps than these three. My ancestors traveled via the Rhine River to get to the ship that would bring them to America. A map of the Rhine River is available.
Town, city, and county maps in the United States are readily found on the website. Some of them even include landowners. A search for Shoreham, Vermont led me to an 1859 map with landowners, schools, ferries, and more shown. My Shoreham Vermont ancestors were in Michigan by then, but collateral line relatives were listed.
The search terms are unlimited. I found searching a wider area was a good place to start and then narrowing it down from there helps. Did you have an ancestor who worked for the railroad? Try searching <state> railroad. My mother talks about taking the train from Kaleva, Michigan to Traverse City, Michigan to go to the doctor as a young woman. A Michigan railroad map shows the route she would have taken.
Are you interested in battle maps where your ancestors served? Search for military maps. There is a vast selection of military maps. Many from the American Revolutionary War time. I have a relative, Harlan Poor, who died at the Battle of Spotsylvania. I found a map of the battle of Spotsylvania.
I have shown you just a few of the maps I found related to my family history. The maps are easy to use, fully downloadable with zoom and rotation features. Underneath each map is a full explanation of the map, including usage rights.
Maps are important to genealogists. If you aren't using maps in your research, I encourage you to. Maps provide clues to where your ancestors might have lived. Maps give you the names of places where your ancestors lived at the time they lived there.
The Leventhal Map Collection is one of the best I have seen. It encompasses Boston, New England and beyond from the 15th Century to the present. I know I will be returning to this collection as I research, I hope you do too.