CensusCD 1970 is the first product to allow access to the results of the 1970
US Census down to the Census tract.
Over 8,500 demographics and geographic identifiers exist for every geographic
area.
The counts are divided into 3 groups: geographic identifiers,
population counts, and housing counts.
In addition, a full set of 1970 tract maps, along with mapping software, has
also been included.
Reports:
If you want an overview of an area, you can simply select the Geographic Area
you want and Run a Snapshot report.
If you want more targeted information than is in the Snapshot report, use
Counts to select the 1970 demographics you want and Run a Summary report.
Export map boundaries:
Run a map of the area and subarea you want. In the map viewer select
file/export. You can export boundaries in Arc View Shape format or MapInfo
MID/MIF format. Water can be clipped off by un-selecting view/water.
The source of the data:
The data for CensusCD 1970 is the Fourth Count Population Summary Tape and
Fourth Count Housing Summary Tape from the US Census Bureau.
Geographic Areas:
CensusCD 1970 contains 6 geographic summarization levels, the total number of
each level is in parentheses: Nation (1) State (51) County (3,137) Tract/BNA
(46,728) Place (22,529) MCD/CCD (35,195)
1970 Boundaries:
1970 Boundaries were created by GeoLytics for tract, State, and County. These
boundaries were built from the 1970 tract Urban Atlas project. These data were
digitized from the 1970 tract maps back in 1975. They represent the first
digital set of boundary files ever created. The state, region, and division
boundaries were taken from 1980 boundaries, since little or no changes occurred
at these levels. Boundaries for 1970 Places and MCD’s were not included
because spatial definitions for these areas were not available.
Suppression:
1970 data is sometimes suppressed by the US Census Bureau to protect
confidentiality. Data is suppressed if its universe does not meet certain
pre-established thresholds. These thresholds are usually between 5 and 15. For
example, if the white population in a geographic area is less than 15, the
demographics for white population will be suppressed. Smaller geographic areas
are more likely to have suppressed data than larger. No data is suppressed at
the state level.
Changes Between the 1970 and 1980 Census:
Geographic areas from the county level and up have changed very little between
the 1980 and 1970 census. But in areas below the county level (MCD, place, and
tract), significant changes may have occurred, such as tract and place splits.
Tracts do not cover 100% of the geographic areas in 1970, or even in 1980, as
they do in 1990 and 2000. Tracts in 1970 are found mainly in urban areas. To
protect confidentiality in 1990, data was imputed. Before 1990 data was
suppressed to protect confidentiality.
Export the file data into other systems like statistical (e.g. SAS,
SPSS), database (e.g. Access, Oracle), spreadsheet (e.g. Excel, 1-2-3), or
mapping (e.g. Arc View, MapInfo) packages.
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