Summary: | In addition to the historic Census files, 1790-1950,
ICPSR archives and distributes Census data acquired from the United States
Census Bureau as well as files prepared by ICPSR and other principal
investigators for the decennial years 1960, 1970, 1980, 1990, and 2000.
These include major sets such as the Summary Tape/Count Files, Master
Enumeration District List (MEDList) files, and Public Use Microdata Samples
(PUMS), as well as various subsets. ICPSR's holdings of 1970 Census data
include a variety of data files acquired from the United States Census
Bureau, a national-coverage file prepared by ICPSR, and files prepared by
other principal investigators. The files from the Census Bureau are separated
into three basic types: Summary Count files, the Master Enumeration
District List (MEDList) files, and Public Use Microdata Samples (PUMS).
Within these collections, various data subsets are available, depending
on the user's needs. For example, to obtain first-count data for
Minnesota's Congressional Districts, the user can download ICPSR 8122,
Summary Count 1B for Minnesota. In addition, ICPSR 0003 contains a subset
of 1970 data that might be useful for users of the 1970 Census of
Population and Housing. This subset, the National Coverage file, contains
all the variables published in the "Advance Report of the General
Population Characteristics" obtained from the First Count of the 1970
Census. The information in this file is presented for all counties and
states in the United States. ICPSR's holdings of the Summary Count files
include Summary Count File 1B (all states), Summary Count File
4A--Population (all states), Summary Count File 4B--Population
(most states), Summary Count File 4C--Population (all states), and
Summary Count 4A--Population and Housing (California). Summary Count
Files present tabulations for small geographic areas. First Count Summary
Files contain about 400 cells of final complete-count population and
housing data, summarized in File A for enumeration districts or
blockgroups, and in File B for states, counties, minor civil divisions
(MCDs) or census county divisions (CCDs), places, and congressional
districts. Second Count Summary Files are subdivided into File A and
File B and contain about 3,500 cells of complete-count population and
housing data summarized for each census tract in File A, and for states,
counties, MCDs or CCDs, places, and Standard Metropolitan Statistical
Areas (SMSAs) in File B. Third Count Summary Files contain 250 cells of
complete-count population and housing data for each city block in
urbanized areas and other areas which have contracted for block
statistics. Fourth Count Summary Files contain 20-, 15-, and 5-percent
sample population and housing characteristics organized into three file
subdivisions. Fifth Count Summary Files contain population and housing
sample data summaries for ZIP code areas. Sixth Count Summary Files
provide detailed tabulations and cross-classifications of sample
population and housing characteristics for states, SMSAs (metropolitan
counties), nonmetropolitan counties of 50,000, and larger cities. The
Master Enumeration District List (MEDList) files provide information for
geographic codes contained on census summary tapes. They provide a
listing of state, county, and area or place names corresponding to
numerical identification codes used on the summary tapes. The 1970
MEDList is an expanded version of the 1960 Geographic Identification
Code Scheme but unlike the 1960 counterpart, the 1970 MEDList contains
block and census tract codes, enumeration district codes, and population
and housing totals for enumeration district and block groups from which
congressional district and other area totals may be summarized. Public
Use Microdata Samples (PUMS) were created by the Census Bureau since
1960 as part of each decennial enumeration and contain individual- and
household-level information from the long-form questionnaires distributed
to a sample of the population enumerated in the Census. The PUMS make it
possible for researchers to create tabulations tailored to their
particular questions and to make time-series comparisons. In 1970, the
Bureau produced three geographic versions and created a Form 1 sample and
a Form 2 sample for each version: the state samples, the metro or county
group samples, and the neighborhood samples. The state and county group
samples have two record types: housing unit records and person records.
For each household, information is provided on the housing unit itself,
as well as on the characteristics of each person in it. Each housing unit
record is followed by a variable number of person records, one for each
member of the household or none if a unit is vacant. A third record type
is also present in the neighborhood characteristics samples: each
neighborhood characteristic record is followed by the housing unit
records sampled within the neighborhood, which in turn are associated
with person records. Because of confidentiality reasons, the 1970 samples
do not identify any places smaller than 250,000 inhabitants. |
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