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Codebook for NHGIS data file 'nhgis0001_ts_nominal_county'
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Contents
    - Data Summary
    - Data Dictionary
    - Geographic Integration Methods
    - Source Data
    - Citation and Use
 
Detailed notes on time series design and comparability are available at: 
    https://data2.nhgis.org/main/all_tst_details 
 
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Data Summary
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Time series layout:     Time varies by column
Geographic level:       County (by State)
Geographic integration: Nominal
Years:                  1970, 1980, 1990, 2000, 2010, 2020
Extent:                 All areas
 
Tables:
 
1. Persons by Race [5*]
   Selected year(s): 1970, 1980, 1990, 2000, 2010, 2020
   Code: B18
 
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Data Dictionary
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Context Fields 
        GISJOIN:     GIS Join Match Code
        STATE:       NHGIS Integrated State Name
        STATEFP:     FIPS State Code
        STATENH:     NHGIS Integrated State Code
        COUNTY:      NHGIS Integrated County Name
        COUNTYFP:    FIPS County Code
        COUNTYNH:    NHGIS Integrated County Code
 
Table 1: (B18) Persons by Race [5*]
    Time series AA: Persons: White (single race)
        B18AA1970:   1970: Persons: White (single race)
        B18AA1980:   1980: Persons: White (single race)
        B18AA1990:   1990: Persons: White (single race)
        B18AA2000:   2000: Persons: White (single race)
        B18AA2010:   2010: Persons: White (single race)
        B18AA2020:   2020: Persons: White (single race)
    Time series AB: Persons: Black or African American (single race)
        B18AB1970:   1970: Persons: Black or African American (single race)
        B18AB1980:   1980: Persons: Black or African American (single race)
        B18AB1990:   1990: Persons: Black or African American (single race)
        B18AB2000:   2000: Persons: Black or African American (single race)
        B18AB2010:   2010: Persons: Black or African American (single race)
        B18AB2020:   2020: Persons: Black or African American (single race)
    Time series AC: Persons: American Indian and Alaska Native (single race)
        B18AC1970:   1970: Persons: American Indian and Alaska Native (single race)
        B18AC1980:   1980: Persons: American Indian and Alaska Native (single race)
        B18AC1990:   1990: Persons: American Indian and Alaska Native (single race)
        B18AC2000:   2000: Persons: American Indian and Alaska Native (single race)
        B18AC2010:   2010: Persons: American Indian and Alaska Native (single race)
        B18AC2020:   2020: Persons: American Indian and Alaska Native (single race)
    Time series AD: Persons: Asian and Pacific Islander and Other Race (single race)
        B18AD1970:   1970: Persons: Asian and Pacific Islander and Other Race (single race)
        B18AD1980:   1980: Persons: Asian and Pacific Islander and Other Race (single race)
        B18AD1990:   1990: Persons: Asian and Pacific Islander and Other Race (single race)
        B18AD2000:   2000: Persons: Asian and Pacific Islander and Other Race (single race)
        B18AD2010:   2010: Persons: Asian and Pacific Islander and Other Race (single race)
        B18AD2020:   2020: Persons: Asian and Pacific Islander and Other Race (single race)
    Time series AE: Persons: Two or More Races
        B18AE2000:   2000: Persons: Two or More Races
        B18AE2010:   2010: Persons: Two or More Races
        B18AE2020:   2020: Persons: Two or More Races
 
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Geographic Integration Methods
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Nominal Integration:

    Nominally integrated tables link geographic units across time according to
    their names and codes, disregarding any changes in unit boundaries. The
    identified geographic units match those from each census source, so the
    spatial definitions and total number of units may vary from one time to
    another (e.g., a city may annex land, a tract may be split in two, a new
    county may be created, etc.). The tables include data for a particular
    geographic unit only at times when the unit's name or code was in use,
    resulting in truncated time series for some areas.
    
    Users should be cautious when interpreting changes in nominally integrated
    time series because a single unit code may refer to distinctly different
    areas at different times. If you are uncertain whether any boundaries
    changed in your areas of interest, we recommend inspecting NHGIS GIS files
    to confirm. (NHGIS supplies GIS boundary files for all units and years in
    nominally integrated time series *except* 1970 places and county
    subdivisions.)
    
    Alternatively, for some topics and time periods, NHGIS provides
    "geographically standardized" time series, which provide data from multiple
    times for a single census's geographic units (e.g., 2000 and 2010 data for
    2010 census units). A disadvantage of standardized time series is that, in
    areas where source units do not nest perfectly within a unit of the standard
    year (e.g., where a source 2000 unit intersects multiple 2010 units), NHGIS
    applies interpolation to standardize the data, a process which may
    occasionally produce substantial errors.

Complete documentation on time series integration methods is available at:
    https://www.nhgis.org/documentation/time-series
 
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Source Data
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Additional documentation on NHGIS data sources is available at:
    https://www.nhgis.org/documentation/tabular-data

Table 1: (B18) Persons by Race [5*]
 
    Time series AA: Persons: White (single race)
        Year: 1970
            Source dataset: 1970 Census: Count 2 - 100% Data [Tracts, Urban Areas, Metro Areas, etc.] 
                Source table: NT1. Sex by Race
                    Universe: Persons
                        Variable: [CEB001] Male >> White
                        Variable: [CEB010] Female >> White
        Year: 1980
            Source dataset: 1980 Census: STF 3 - Sample-Based Data
                Source table: NT12. Race
                    Universe: Persons
                        Variable: [DFB001] White
        Year: 1990
            Source dataset: 1990 Census: STF 1 - 100% Data
                Source table: NP6. Race
                    Universe: Persons
                        Variable: [EUY001] White
        Year: 2000
            Source dataset: 2000 Census: SF 1a - 100% Data [Areas Larger Than Block Groups]
                Source table: NP007A. Population by Race
                    Universe: Persons
                        Variable: [FMR001] White alone
        Year: 2010
            Source dataset: 2010 Census: SF 1a - P & H Tables [Blocks & Larger Areas]
                Source table: P3. Race
                    Universe: Total population
                        Variable: [H7X002] White alone
        Year: 2020
            Source dataset: 2020 Census: DHC - P & H Tables [Blocks & Larger Areas]
                Source table: P3. Race
                    Universe: Total population
                        Variable: [U7J002] White alone
 
    Time series AB: Persons: Black or African American (single race)
        Year: 1970
            Source dataset: 1970 Census: Count 2 - 100% Data [Tracts, Urban Areas, Metro Areas, etc.] 
                Source table: NT1. Sex by Race
                    Universe: Persons
                        Variable: [CEB002] Male >> Negro
                        Variable: [CEB011] Female >> Negro
        Year: 1980
            Source dataset: 1980 Census: STF 3 - Sample-Based Data
                Source table: NT12. Race
                    Universe: Persons
                        Variable: [DFB002] Black
        Year: 1990
            Source dataset: 1990 Census: STF 1 - 100% Data
                Source table: NP6. Race
                    Universe: Persons
                        Variable: [EUY002] Black
        Year: 2000
            Source dataset: 2000 Census: SF 1a - 100% Data [Areas Larger Than Block Groups]
                Source table: NP007A. Population by Race
                    Universe: Persons
                        Variable: [FMR002] Black or African American alone
        Year: 2010
            Source dataset: 2010 Census: SF 1a - P & H Tables [Blocks & Larger Areas]
                Source table: P3. Race
                    Universe: Total population
                        Variable: [H7X003] Black or African American alone
        Year: 2020
            Source dataset: 2020 Census: DHC - P & H Tables [Blocks & Larger Areas]
                Source table: P3. Race
                    Universe: Total population
                        Variable: [U7J003] Black or African American alone
 
    Time series AC: Persons: American Indian and Alaska Native (single race)
        Year: 1970
            Source dataset: 1970 Census: Count 2 - 100% Data [Tracts, Urban Areas, Metro Areas, etc.] 
                Source table: NT1. Sex by Race
                    Universe: Persons
                        Variable: [CEB003] Male >> Indian
                        Variable: [CEB012] Female >> Indian
        Year: 1980
            Source dataset: 1980 Census: STF 3 - Sample-Based Data
                Source table: NT12. Race
                    Universe: Persons
                        Variable: [DFB003] American Indian, Eskimo and Aleut: American Indian
                        Variable: [DFB004] American Indian, Eskimo and Aleut: Eskimo
                        Variable: [DFB005] American Indian, Eskimo and Aleut: Aleut
        Year: 1990
            Source dataset: 1990 Census: STF 1 - 100% Data
                Source table: NP6. Race
                    Universe: Persons
                        Variable: [EUY003] American Indian, Eskimo, or Aleut
        Year: 2000
            Source dataset: 2000 Census: SF 1a - 100% Data [Areas Larger Than Block Groups]
                Source table: NP007A. Population by Race
                    Universe: Persons
                        Variable: [FMR003] American Indian and Alaska Native alone
        Year: 2010
            Source dataset: 2010 Census: SF 1a - P & H Tables [Blocks & Larger Areas]
                Source table: P3. Race
                    Universe: Total population
                        Variable: [H7X004] American Indian and Alaska Native alone
        Year: 2020
            Source dataset: 2020 Census: DHC - P & H Tables [Blocks & Larger Areas]
                Source table: P3. Race
                    Universe: Total population
                        Variable: [U7J004] American Indian and Alaska Native alone
 
    Time series AD: Persons: Asian and Pacific Islander and Other Race (single race)
        Year: 1970
            Source dataset: 1970 Census: Count 2 - 100% Data [Tracts, Urban Areas, Metro Areas, etc.] 
                Source table: NT1. Sex by Race
                    Universe: Persons
                        Variable: [CEB004] Male >> Japanese
                        Variable: [CEB005] Male >> Chinese
                        Variable: [CEB006] Male >> Filipino
                        Variable: [CEB007] Male >> Hawaiian
                        Variable: [CEB008] Male >> Korean
                        Variable: [CEB009] Male >> Other
                        Variable: [CEB013] Female >> Japanese
                        Variable: [CEB014] Female >> Chinese
                        Variable: [CEB015] Female >> Filipino
                        Variable: [CEB016] Female >> Hawaiian
                        Variable: [CEB017] Female >> Korean
                        Variable: [CEB018] Female >> Other
        Year: 1980
            Source dataset: 1980 Census: STF 3 - Sample-Based Data
                Source table: NT12. Race
                    Universe: Persons
                        Variable: [DFB006] Asian and Pacific Islander: Japanese
                        Variable: [DFB007] Asian and Pacific Islander: Chinese
                        Variable: [DFB008] Asian and Pacific Islander: Filipino
                        Variable: [DFB009] Asian and Pacific Islander: Korean
                        Variable: [DFB010] Asian and Pacific Islander: Asian Indian
                        Variable: [DFB011] Asian and Pacific Islander: Vietnamese
                        Variable: [DFB012] Asian and Pacific Islander: Hawaiian
                        Variable: [DFB013] Asian and Pacific Islander: Guamanian
                        Variable: [DFB014] Asian and Pacific Islander: Samoan
                        Variable: [DFB015] Asian and Pacific Islander: Other
        Year: 1990
            Source dataset: 1990 Census: STF 1 - 100% Data
                Source table: NP6. Race
                    Universe: Persons
                        Variable: [EUY004] Asian or Pacific Islander
                        Variable: [EUY005] Other race
        Year: 2000
            Source dataset: 2000 Census: SF 1a - 100% Data [Areas Larger Than Block Groups]
                Source table: NP007A. Population by Race
                    Universe: Persons
                        Variable: [FMR004] Asian alone
                        Variable: [FMR005] Native Hawaiian and Other Pacific Islander alone
                        Variable: [FMR006] Some other race alone
        Year: 2010
            Source dataset: 2010 Census: SF 1a - P & H Tables [Blocks & Larger Areas]
                Source table: P3. Race
                    Universe: Total population
                        Variable: [H7X005] Asian alone
                        Variable: [H7X006] Native Hawaiian and Other Pacific Islander alone
                        Variable: [H7X007] Some Other Race alone
        Year: 2020
            Source dataset: 2020 Census: DHC - P & H Tables [Blocks & Larger Areas]
                Source table: P3. Race
                    Universe: Total population
                        Variable: [U7J005] Asian alone
                        Variable: [U7J006] Native Hawaiian and Other Pacific Islander alone
                        Variable: [U7J007] Some Other Race alone
 
    Time series AE: Persons: Two or More Races
        Year: 1970
            *NOT AVAILABLE for this time*
        Year: 1980
            *NOT AVAILABLE for this time*
        Year: 1990
            *NOT AVAILABLE for this time*
        Year: 2000
            Source dataset: 2000 Census: SF 1a - 100% Data [Areas Larger Than Block Groups]
                Source table: NP007A. Population by Race
                    Universe: Persons
                        Variable: [FMR007] Two or more races
        Year: 2010
            Source dataset: 2010 Census: SF 1a - P & H Tables [Blocks & Larger Areas]
                Source table: P3. Race
                    Universe: Total population
                        Variable: [H7X008] Two or More Races
        Year: 2020
            Source dataset: 2020 Census: DHC - P & H Tables [Blocks & Larger Areas]
                Source table: P3. Race
                    Universe: Total population
                        Variable: [U7J008] Two or More Races
 
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Citation and Use of NHGIS Data
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        IPUMS National Historical Geographic Information System: Version 20.0 
        [dataset]. Minneapolis, MN: IPUMS. 2025. 
        http://doi.org/10.18128/D050.V20.0

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