Maps can really add a lot to any genealogy research. I posted earlier about some sources of Sanborn Maps. Here is another example of maps that can be an addition to your genealogy research. Brooklyn Genealogy Wesbite has copies of Johnson Maps which show tax parcels, businesses and landowners.
The Johnson Map atlas’s are very helpful. I found my ancestor Conrad Fleck in Jamaica Queens New York on this 1873 map. The map is a great resource to to find neighbors and other family members who lived in the community.