Use Cadastral Mapping to find your ancestors

Standard Atlas of Calhoun County, Iowa
Geo. A. Ogle & Co. 1911

I would assume that very few genealogical researchers are aware of cadastral mapping. The example above is from The University of Iowa Libraries, Iowa Digital Collection. If you click on the image, you can see that the map contains the boundaries of each farm with the name of the owner. This type of map is commonly used and published around the world. The term "cadastre" is defined as follows:

an official register of the quantity, value, and ownership of real estate used in apportioning taxes

 Since taxation is historically a common issue, therefore these maps exist and can be used by genealogists to locate ancestral lands and identify the boundaries. Here is an explanation of cadastral mapping from the U.S. Department of the Interior, Bureau of Land Management:

Cadastral surveys deal with one of the oldest and most fundamental facets of human society-ownership of land. 

They are the surveys that create, mark, define, retrace, or reestablish the boundaries and subdivisions of the public lands of the United States. 

They are not like scientific surveys of an informative character, which may be amended due to the availability of additional information or because of changes in conditions or standards of accuracy. Although cadastral surveys employ scientific methods and precise measurements, they are based upon law and not upon science. 

Cadastral surveys are the foundation upon which rest title to all land that is now, or was once, part of the Public Domain of the United States.

Some of the maps show the property boundaries with numbers or other designations for reference to the ownership of the land. You may have to dig a little deeper into the local records to see the actual land ownership. However, once you have a parcel description, which you can get from either looking at other land records or other pertinent records, you can usually find a map showing that parcel and adjacent parcels. It is hard not use general descriptions in this area of mapping because almost every local mapping agency has a different system. Many U.S. states and counties have a local mapping system showing land ownership with detailed maps online. I used the one for Maricopa County, Arizona rather frequently. Here is an example of a subdivision map from the Maricopa County Assessor's Office. The map is interactive and when you mouse over any parcel, the ownership data pops up.

In Arizona, you can then go to the Maricopa County Recorders office and trace the ownership of the parcel. In effect, you can either start with historical ownership obtained by reference in a probate file, land records or other references and then reconstruct the property boundaries from the title history. Always search for historical maps of the same area. Here is another example from the Canadian County Atlas Digital Project:

Once you become aware of the existence of this type of map, they seem to pop up everywhere. Here are some links to interesting cadastral mapping websites:

• Montana Cadastral
• Cadastral Survey
• Mathews County Virginia Cadastral Maps
• Michigan County Histories and Atlases
• In Search of Your Canadian Past
• Iowa Counties Historic Atlases - Iowa Digital Library
• State Lib Oh County Atlases - Ohio Memory
• Historic Atlases of Cleveland and Cuyahoga County, Ohio
• Montgomery County and Pennsylvania Atlas - 1871

The list can go on and on. This type of map is also common in Europe and other parts of the world. Keep looking.