Description

SEA stands for State Economic Area, a concept described fully in Donald J. Bogue, State Economic Areas (Washington, D.C., 1951). SEAs are generally either single counties or groups of contiguous counties within the same state that had similar economic characteristics when they were originally defined, just prior to the 1950 census.

The Census Bureau first used SEAs in 1950, and the concept was applied retroactively to the 1940 sample. The IPUMS constructed SEAs for 1850-1930 by combining counties to match, as closely as possible, the components of the 1940-1950 SEAs. However, shifts in county boundaries, primarily resulting from the creation of new counties as populations shifted and grew, mean that these earlier SEAs do not always contain exactly the same territory as their 1940-1950 counterparts (see COUNTYICP). This is particularly true of areas with relatively small populations in earlier years, which generally had more unstable county boundaries.

For 1940 and 1950, SEAs with fewer than 100,000 residents were combined to form SEAs exceeding 100,000 residents, to meet confidentiality requirements that are currently in effect for the 1950 sample and that were in effect for the 1940 sample at the time the IPUMS SEAs were last constructed. The resulting SEAs were applied to previous census years.

The 1950 census did not create SEAs for Alaska and Hawaii; the IPUMS assigns them each a single, separate SEA value, for those samples that contain these states (see STATEICP). Military reservations in 1910 are also coded separately from the SEAs that contained them. Although West Virginia did not exist as a state in 1850, SEAs that later became part of West Virginia are coded in all years as West Virginia. Finally, a few SEAs were unidentifiable throughout the 1850-1920 period. These SEAs are coded as missing, within the state that contained them.

SEA is a 3-digit numeric variable which identifies the household's State Economic Area, a concept described fully in Donald J. Bogue, State Economic Areas (Washington, D.C., 1951). SEAs are generally either single counties or groups of contiguous counties within the same state that had similar economic characteristics when they were originally defined, just prior to the 1950 census. The Census Bureau first used SEAs in 1950, and the concept was applied retroactively to the 1940 sample. The IPUMS constructed SEAs for 1850-1930 by combining counties to match, as closely as possible, the components of the 1940-1950 SEAs. SEA specific variable codes for missing, edited, or unidentified observations, observations not applicable (N/A), observations not in universe (NIU), top and bottom value coding, etc. are provided below by Census year (and data sample if specified).

SEA Specific Variable Codes
See SEA codes for details regarding SEA codes.

1940 100%: SEA codes are provided for about 50% of records in the 1940 complete count data file. If an SEA code is not available the value will be blank.

User Note: The 1950 census did not create SEAs for Alaska and Hawaii; the IPUMS assigns them each a single, separate SEA value, for those samples that contain these states (see STATEFIP or STATEICP). Military reservations in 1910 are also coded separately from the SEAs that contained them. Although West Virginia did not exist as a state in 1850, SEAs that later became part of West Virginia are coded in all years as West Virginia. Finally, a few SEAs were unidentifiable throughout the period of 1850-1920. These SEAs are coded as missing, within the state that contained them.

Comparability

The county components of the 1940 and 1950 SEAs are the same. For previous years, SEA boundaries differ only insofar as county boundaries shifted.

SEA boundaries are based upon the economic characteristics of counties in 1950. Counties within a particular SEA may or may not have been as economically homogeneous in previous years. Even when this is not the case, SEA is still useful for consistently identifying geographical units smaller than states and larger than counties.

For the post-1950 period, the Census Bureau designated other geographic entities to meet confidentiality requirements. These include 1970 county groups of 250,000+ population (in CNTYGP97), 1980 county groups of 100,000+ population (in CNTYGP98), 1990 Public Use Microdata Areas (PUMAs) of 100,000+ population (in PUMA), Public Use Microdata Areas (PUMAs) of 100,000+ population for the 5 percent sample of the 2000 census (in PUMA), and Super-Public Use Microdata Areas (Super-PUMAs) of 400,000+ population for the 1 percent sample of the 2000 census (in PUMASUPR).

Universe

Availability

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• 1990: --
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• 1960: --
• 1950: 1%
• 1940: All samples
• 1930: All samples
• 1920: All samples
• 1910: All samples
• 1900: All samples
• 1880: All samples
• 1870: All samples
• 1860: All samples
• 1850: All samples

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• 1910: --

Flags

Editing Procedure

There is no editing procedure available for this variable.