Overlay Enumeration District Maps onto Modern Street Maps to Find Relatives in Census by Place

[UPDATE (23 March 2022): Ancestry has recently released its own 1950 census enumeration district map tool. The Ancestry tool is very easy to use, and it does about 80% of the Steve Morse/Georeferencer method described below (including the most important part: given a place, getting an E.D. number, which will be used to go straight to census pages). The Ancestry tool does not offer a side-by-side map comparisons, does not allow for the changing of base maps, does not allow for fine-tuning of the map alignments, and does not create nice-looking overlay images to save; BUT, these are minor points, relative to the main goal of getting quickly to census pages. Thanks to Sheri Snodgrass for sharing the announcement of this new tool at Ancestry, which you can find here: https://www.ancestry.com/discoveryui-content/district-map/62308.]

My parents and several aunts and uncles were born in the decade before the 1950 census. The 1950 census data will be made public soon, and though it will take some time for the census to be fully and accurately indexed to be searchable by name, starting on April 1, 2022, if you know the general place where a family was living, then you can find the census page(s) for that place. This post steps through the process I used to prepare to find my relatives in their first appearance in the census. Here are the broad steps, which are then further described in more detail below.

  1. Gather the names, and, as best you can, the addresses or place where they lived during the spring of 1950;
  2. Find and download the census enumeration map for that place using SteveMorse.org; and
  3. Overlay the ED map onto a modern street map using Georeferencer.

Later, even after the census is fully indexed, you can use steps two and three described below to find census pages which enumerate a place by overlaying an enumeration district map over a modern street map.

1. Gather Names of People to Find in Census and their Locations

If, like me, you have a ready list of people who you are interested in finding in the 1950 census, then this step is nearly complete; you need only, as best you are able, to note the place where they were living in the spring of 1950. I simply asked my parents, aunts, and uncles, as best they could remember, where they were living then. You may also consult your family history database of the previous address of that family before 1950.

If you don’t have a ready list of people who you are interested in finding in the 1950 census, you can generate a list with your family history database. Here are the steps I used in RootsMagic 7 to create a rough list; this list will not be perfect as it may include some people it shouldn’t, and it will miss some people it should; the accuracy of your list will depend on the accuracy and completeness of the information already in your database, especially birth and death dates. With that in mind:

  1. Create a “Group” of people meeting your search criteria: Search > Named groups > Manage groups > New > name the group something like “1950 Census Candidates”;
  2. Select people for your group:
    • Mark group > Select people by data fields > “birth date is after 1840”; then
    • Unmark group > Clear people by data fields > “death date is before 1950”; then
    • Unmark group > Clear people by data fields > “birth date is after 1950.”
Figure 1: RootsMagic 7 dialog to REMOVE census candidates from group who would NOT have been present during 1950 census.

You may wish to further refine your 1950 census candidate list by adding or removing people by, for example, those you are actively researching or those who hold special interest.

Next, for this list of possible 1950 census research candidates, filter the list by those for whom you have a possible location, noting especially the county.

2. Get Enumeration District Maps using SteveMorse.org

Although online genealogy research sites will be using artificial intelligence to create a first, rough draft of a name index to the 1950 census, that will take some time and its accuracy is unknown; in time, further indexing and error correction will be done by volunteers. A researcher may choose not to wait or rely upon uncertain indexing to begin browsing census population schedules on April 1, 2022. If a researcher knows at least the general area of a 1950 census candidate, then the researcher can browse or scan pages for that area. The census administrators used “enumeration districts” to assign areas to census takers; an enumeration district, according to the National Archives, is “generally the area a single enumerator, or census taker, could cover in one census period, approximately two to four weeks” (see that National Archives article for more information about enumeration districts and their maps). To narrow the scope of a researcher’s task, overlaying an enumeration district map on top of a modern street map may enable the researcher to focus their line-by-line browsing of census page images by dramatically lessening the number of pages to review. Perhaps the easiest way to find and download a specific 1940 or 1950 enumeration district map is using one of the tools at SteveMorse.org:

Figure 2: Navigating the 1940/1950 Enumeration District Maps in One Step tool at SteveMorse.org website.

As seen in the image above, the researcher selects the decade, state, county, and, if able, the city in which the 1950 census candidate may have resided. Clicking the “Get ED Map Images” button leads the researcher to a page from where the ED map images can be viewed and saved, as seen below. We will save the JPEG image to the researcher’s computer for overlaying on to a street map.

Figure 3: Saving your enumeration district map to your computer.

The map image that is downloaded, in this example, as shown below, depicts the boundaries of the several (perhaps 36) enumeration districts into which Ashe County, North Carolina was divided for the 1950 census. Following, the process to overlay this enumeration district map image overtop of a street map is described.

Figure 4: 1950 Enumeration District map for Ashe County, North Carolina. The orange lines are the boundaries of the enumeration districts into which Ashe County was divided. A single census taker would have been expected to gather data in that area over a period of two to four weeks. Click to enlarge.

3. Overlay ED Map onto Modern Street Map Using Georeferencer

We expect maps today to mirror perfectly the territory they depict, if only at a smaller scale, and because maps today can be created from satellite images, many do. In the past, however, map-making was a more artistic endeavor. This difference can be seen when a semi-transparent older map is placed on top of a modern map; the features on the maps do not perfectly align, and in some cases may be substantially misaligned.

Figure 5: A transparent enumeration district map may be placed over a modern street map, or, as seen here, over a terrain map created from satellite images. Ashe County, in the most northwestern corner of North Carolina, borders Virginia and Tennessee. A slider tool allows the researcher to adjust the level of transparency from completely opaque to nearly invisible, revealing the Appalachian geography of the region or modern streets and highways. Click to enlarge.

The misalignment between an older map overlaid on top of a newer map can be corrected using a tool recommended at and by David Rumsey Map Collection, Georeferencer. The example shown here was created using a free account at https://www.georeferencer.com/.

To understand how an older map (which might be substantially out of alignment with a newer map) nevertheless might be correctly aligned with the newer map, imagine that the older map was able to stretched, as if printed on Silly Putty or a rubber balloon. The Georeferencer tool allows the researcher to “pin” a map feature, say a bridge or highway intersection, on the older map to the correct location on the newer map underneath, of the same map feature, say again that same bridge or highway intersection. Further, a slider tool allows the researcher to adjust the level of transparency from completely opaque to nearly invisible, revealing the underlying geography of the region of a terrain map or modern buildings and highways of a street map, and allowing the researcher to use the pins to correlate identical locations on both maps. Through trial-and-error, I found that pinning the location of bridges and highway intersections works well (better than buildings, homes, churches, and other structures, which, for clarity, may have been shown on older maps to be further from roads than the scale of the map would suggest). To pin locations, the researcher has a choice of views for the old and new maps: side-by-side or overlay. A side-by-side comparison is shown here; to align the two maps, a blue pin placed at a highway intersection on both maps allows the mapping software “stretch” or transform the old map as needed to align perfectly with the new map.

Figure 6: A side-by-side comparison of a modern satellite image and a georeferenced 1950 ED map for the same area. At the center of the blue circles, blue pins can be seen; the blue pins, placed at highway intersections or bridges, ensure that old and new maps are correctly aligned. The red square highlights a black square on the ED map showing the home of the researcher’s mother and grandparents in 1950. Click to enlarge.

After pinning or georeferencing several locations between the old and new maps, the imaging software understands how to stretch or transform the old map so that it more accurately aligns to the satellite-derived map underneath. USE THE SLIDER BELOW to compare a properly aligned or georeferenced ED map side-by-side with the identical area in Google Maps street view.

Figure 7: INTERACTIVE SLIDER: You can slide the arrows above to compare a properly aligned 1950 ED map with a modern Google Maps street map of the same area. Again, the orange lines on the ED map to the left are the boundaries of the enumeration districts into which Ashe County was divided. At the Georeferencer.com website, the researcher can zoom-in and zoom-out to adjust the scale of the map, and can adjust the level of transparency of the map overlay.

The reward: Fun! And quicker access to meaningful census data.

The 1950 enumeration district map above informs the researcher that his mother and grandparents will be found on the census sheets labeled “West Jefferson Township, enumeration district 5-35, Ashe County, North Carolina.” This georeferencing work with ED maps overlaid upon current street maps allow the researcher to determine correct enumeration districts and therefore browse those few, select census pages for the lines containing their census information.

3 thoughts on “Overlay Enumeration District Maps onto Modern Street Maps to Find Relatives in Census by Place

  1. Great post! I wanted to share with you an alternative to the Georeferencer site. Since enumeration maps are public domain, you can upload them to wikipedia. More specifically, Wikimedia Commons. All the 1950 enumeration maps are already uploaded there. Then you can use Wikimaps Warper to georeference them. This will put the map you just georeferenced into a place that is easily accessible to everyone.

    Here’s an example of a map I uploaded:

    Here’s the georeferenced version (linked to from above):

    Here’s the wikipedia article it’s used in:

    Keep up the great work!

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