Digital Spatial Data

US Census

1970

The 1970 Census was the first Census for which the Bureau of the Census released series of Summary Statistic Files (Counts) as a part of the regular program for dissemination of data. Major series files are as follow:

First Count Files A & B (Summary Statistic File 1A & 1B)
Based on the complete, 100%, count data, the file 1A data files give summaries for each state and for each enumeration district (ED) or block group, and the file 1B data files give summaries for each state, county, MCDs or CCDs, places, and congressional districts - compatible to the Summary File 1 (SF1) of the Census 2000.

Second Count Files A & B (Summary Statistic File 2A & 2B)
Based on the complete, 100%, count data, the file 2A data files give summaries for census tracts in tracted areas, and the file 2B data files give summaries for Selected Census Areas -- states, SMSAs, urbanized areas, places, counties and MCDs or CCDs - compatible to the Summary File 1 (SF1) of the Census 2000.

Third Count Files (Summary Statistic File 3)
Based on the complete, 100%, count data, the third count data files give summaries for city blocks and census tracts in blocked areas - compatible to the Summary File 1 (SF1) of the Census 2000.

Fourth Count Files A, B & C (Summary Statistic File 4A, 4B & 4C)
Based on the sample data, the file 4A data files give summaries for census tracts in tracted areas, and the file 4B data files give summaries for MCDs or CCDs, and the file 4C data files give summaries for selected census areas -- states, SMSAs, urbanized areas, places, and counties; separate tallies are shown for the Hispanic population as well as for the total Black and White population - compatible to the Summary File 3 (SF3) of the Census 2000.

Fifth Count Files A, B & C (Summary Statistic File 5A, 5B & 5C)
Based on the sample data, the file 5A data files give summaries for for three-digit zipcode areas, and the file 5B data files give summaries for five-digit zipcode areas in SMSAs, and the file 5C data files give summaries for EDs or block groups, MCDs or CCDs, and census tracts; separate tallies are shown for the Hispanic population as well as for the total Black and White population - compatible to the Summary File 3 (SF3) of the Census 2000.

 1970 Data Sources 

Inter-University Consortium For Political and Social Research (ICPSR) (web)
http://www.icpsr.org/
Fourth Count File A, B & C  (Summary Statistic File 4A, 4B & 4C) data are available for downloading for the UWM students and faculty for education use. Search for the data using keyword "census and 1970 and count", for example. Data files are in the ascii format, thus require basic database knowledge.

1970 Census of Population and Housing. Census Tract (book & microfilm) (UWM Libraries)
Call Number - Book      :  HA201 1970 .A54
Call Number - microfilm :  HA4
Equivalent to the Fourth Count Files, these traditional data resources organized by SMSA are available from the UWM Libraries. It is good enough for users who need limited amount of census tract level data. Census tract maps area included in the microfilms. Printed index/guide to microfilm set located in Microforms Index area and in Reference, classed: HA 195 .R4x 1975.

1970 Census of Housing. Block Statistics, Milwaukee, Wis, Urbanized Area (microfilm) (UWM Libraries)
Call Number - microfilm :  HA2
Housing block statistics are available as microfilms in the UWM Libraries. Block maps are also included.

 1970 Boundary Data Sources 

Unfortunately, there is no digital 1970 boundary file available for the UWM GIS users. I would recommend to edit an available public domain census boundary file to fit to the 1970 boundary; for example, one can create a 1970 census tract boundary file by editing 1990 tract boundary file. Luckily, paper maps are available from the microfilms mentioned in the section above. Scan the map (or save it as PDF and then convert to the TIFF or JPEG), georeference the scanned image in GIS and overlay a source boundary file on top of the scanned image, and edit it based on the georeferenced map image.

 1970 Census Geography 

Standard Metropolitan Statistical Area (SMSA)
SMSA is an integrated economic and social unit with a recognized large population nucleus. In 1970, SMSA's were designated by the Office of Federal Statistical Policy and Standards of the Department of Commerce. There were 238 defined SMSA's in the United States (exclusive of Puerto Rico) at the time of the 1970 census. 

Zip code Area
ZIP code areas were a new type of area for which the 1970 census data were summarized. Fifth count summary tapes are the only source for population and housing data from the 1970 census by ZIP code areas. Nationwide, ZIP code data are available for three-digit ZIP-codes, except that data for five-digit ZIP code areas are provided within SMSA's. ZIP code areas seldom cross state lines, but frequently cross county, SMSA, and city boundaries. 

County
Counties are the primary political and administrative divisions of the states. In Louisiana, such divisions are called parishes, and in Alaska 29 census divisions were established as county equivalents in 1970 for statistical purposes. In 1970, there were 3,141 counties or county equivalents. 

Census County Division (CCD)
In 1970, CCD's were defined in 21 states (AL, AZ, CA, CO, DE, FL, GA, HA, ID, KY, MT. NM, ND, OK, OR, SC, TN, TX, UT, WA, and WY) where MCD's were found to be unsuitable for presenting statistics. CCD's are defined with boundaries that seldom change and can be easily located (e.g., roads, highways, streams, railroads, power lines, and bridges). Large incorporated places are usually recognized as separate CCD's, even though their boundaries may change as a resulyt of annexations. Cities with 10,000 or more inhabitants generally are separate CCD's and some incorporated places with as few as 1,000 inhabitants may be separate CCD's in very rural places. There were approximately 7,000 CCD's in the 1970 census.  

Minor Civil Division (MCD)
In 1970, MCD's were defined as the primary political or administrative subdivisions of counties. They are most frequently known as townships, but in some states include towns, precincts, and magesterial districts. MCD tabulations were made for the 1970 census in 29 states. In 1970, over 24,000 MCD's were recognized by the Bureau of the Census.

Place
In 1970, the term 'place' as used by the Bureau of the Census, refers to a concentration of population, regardless of the existence of legally prescribed limits, powers, or functions. Most of the places identified in the 1970 census are incorporated as cities, towns, villages, or boroughs. There were almost 21,000 places recorded in the 1970 census. 

Enumeration District (ED)
In 1970, ED's were areas averaging about 800 people or 250 housing units and were defined by the Bureau of the Census to control the collection and tabulation of 1970 census data for the conventional enumeration areas. ED's were defined as representing an adequate enumerator workload and the boundaries of the ED do not cross boundaries of any area for which data were to be tabulated (except blocks). About 142,000 ED's were created for the 1970 census. 

Census Tract
In 1970, census tracts were designed to be relatively homogeneous areas at the time of establishment with respect to population characteristics, economic status, and living conditions. The average tract contained about 4,000 residents. All SMSA's recognized at the time of the 1970 census were completely tracted. In addition, over 2,300 census tracts were recognized in non-SMSA cities and counties. The 1970 census total was about 34,700 tracts. 

Block Group
In 1970, block groups were combinations of blocks having an average population of about 1,000. Block groups were subdivisions of census tracts in the urbanized area of the 145 SMSA's where ED data are not available.  

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