NARA expects to digitally release the 1950 population census schedules for researcher use on April 1, 2022, which is 72 years after the official 1950 census day of April 1, 1950.  This is the 52nd in a series of blog posts on the 1950 census.

In September 1949, the Census Bureau's Field Division set forth the principles and methods by which its staff were to design Enumeration Districts (EDs) for the forthcoming 1950 census in an instruction manual entitled "How to Establish Enumeration District Boundaries."  This manual provides insight into the goals that the Bureau wanted to accomplish in this important planning task.  Seven principal goals or objectives were to be achieved:

(1)  The EDs must not overlap so no one would be counted twice.

(2)  The EDs must be established so that statistics for each planning area (city, ward, etc.) could be properly tabulated.

(3)  The EDs must be small enough to permit the enumerators to complete their work in the time allotted.

(4)  The 1940 ED boundaries must be observed wherever possible.

(5)  Open-country EDs (rural areas) should not contain more than 1,400 inhabitants or 200 farms, with an ideal population size of 1,200.

(6)  Closely-settled EDs (city, town, and village areas) should not contain more than 1,000 inhabitants, with an ideal population size of 900.

(7)  The features used to divide areas into EDs must be chosen so that enumerators can easily identify them. 

The Census Bureau's Geography Division, which had collected maps from a variety of federal, state, and county sources, marked them according to this color scheme:

(1)  RED LINES - County and Minor Civil Division (MCD) boundaries

(2)  GREEN LINES - Incorporated place (city) boundaries and ward boundary lines

(3)  PURPLE LINES - Unincorporated place boundaries

(4)  BLUE LINES - Congressional District boundaries

(5)  BROWN LINES - Census tract boundaries in metropolitan areas

With this preliminary work done, Field Division staff could then map EDs using these principles:

(1)  ED boundaries could not cross precinct, ward, or city boundaries of any area for which separate census statistics were required.  In other words, an ED could not include parts of two precincts, parts of two wards, or part of a city and an area outside the city limits.

(2)  The 1940 ED boundaries would be reused when possible.  Circumstances that made reuse impossible were:

  • Changes in city, ward, or precinct boundaries that divided the 1940 ED between two wards or precincts, etc.
  • A road or other geographic feature used as a 1940 census boundary no longer existed or was relocated.
  • A geographic feature, such as a canyon, reservoir, mountain, etc., broke the ED into widely separated parts that would cause the enumerator difficulty in traveling from one part to another.
  • Changes in population that made the 1940 ED too big to be covered by one enumerator in the time allotted.

(3)  The ED should not contain more than 200 farms. 

(4)  The ED should not contain more than 1,000 persons in closely-settled areas or more than 1,400 persons in open country areas.  An ED's population could be estimated by multiplying the number of dwelling units by 3.5. 

(5)  1940 EDs that contained fewer than 300 persons were to be combined with adjoining EDs whenever possible if doing so did not violate the preceding principles.  In addition, 1940 EDs that were small in population but large in geographic area (a common situation in western states) were not to be combined with adjoining EDs.

(6)  Rules of thumb for dividing 1940 EDs into smaller EDs due to population growth are shown in the table below:

1940 Census EDs in Closely-Settled Areas1940 Census EDs in Open-Country Areas
301 to 1,000 population:  Use as a 1950 ED301 to 1,400 population:  Use as a 1950 ED
1,001 to 1,800 population:  Split into 2 1950 EDs1,401 to 2,400 population:  Split into 2 1950 EDs
1,801 to 2,700 population:  Split into 3 1950 EDs2,401 to 3,600 population:  Split into 3 1950 EDs
2,701 to 3,600 population:  Split into 4 1950 EDs3,601 to 4,800 population:  Split into 4 1950 EDs
3,601 to 4,500 population:  Split into 5 1950 EDs4,801 to 6,000 population:  Split into 5 1950 EDs
4,501 to 5,400 population:  Split into 6 1950 EDsLarger areas:  Split into 1950 EDs having approximately 1200 inhabitants
Larger areas:  Split into 1950 EDs having approximately 900 inhabitants

(7)  Nonpolitical ED boundaries must be "acceptable for census use, that is, boundaries that an enumerator may be expected to locate with a minimum of difficulty," such as roads, railroads, and bodies of water, such as streams, rivers, canals, bays, inlets, lakes, bays, and so forth.  Boundaries to be avoided, unless absolutely necessary, included cemetery boundaries, park boundaries, sections lines, township lines, and unnamed streets.

(8)  Special enumeration areas (institutional EDs) were established for:

  • State and federal prisons, reformatories, and institutions for the insane or feeble-minded
  • Roman Catholic institutions having 25 or more residents
  • Institutions such as orphanages, old peoples homes, and so forth, having 100 or more inmates or residents
  • Hotels with 100 or more rooms or apartments
  • Apartment buildings having 100 or more apartments in cities with 500,000 or more inhabitants
  • Veterans hospitals, Public Health hospitals, and other federal hospitals, excluding hospitals on military posts
  • Nonfederal hospitals with 1,000 or more beds or providing for nurse and intern training
  • Army, Air Force, and Navy installations
  • Selected U.S. Coast Guard installations that have resident personnel and that are not easily accessible to the enumerator of the adjacent ED

(9) Special enumeration areas that fall within two or more Minor Civil Divisions, wards, etc., were to be divided into two or more EDs. 

Note, however, that even if the 1940 ED boundaries were reused in 1950, the 1950 ED number was different than the 1940 ED number in the vast majority of cases.  In the next post, we'll discuss how Enumeration Districts were numbered. 

Source:  Images 4 to 16 of "Binder 190-G - Field Mapping Instructions - 17FLD-Mapping 100, "How to Establish Enumeration District Boundaries" (September 1949) (National Archives Identifier 214451610); 17th Decennial Census Reference Materials, 1947-1954 (National Archives Identifier 2990119); Record Group 29, Records of the Bureau of the Census; National Archives, Washington, DC.