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Codebook for NHGIS data file 'nhgis0004_ds7_1840_county'
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Contents
    - Data Summary
    - Data Dictionary
    - Citation and Use
 
Additional documentation on NHGIS data sources is available at: 
    https://www.nhgis.org/documentation/tabular-data 
 
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Data Summary
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Year:             1840
Geographic level: County (by State)
Dataset:          1840 Census: Population & Other Data [US, States & Counties]
   NHGIS code:    1840_cPopX
   NHGIS ID:      ds7
 
Tables:
 
1. Total Urban Population in Cities of 25,000 and Over
   Universe:    Urban Persons in Cities of 25,000 and Over
   Source code: NT3
   NHGIS code:  ACW
 
2. Number of Students by Type of Learning Institutions
   Universe:    Students
   Source code: NT14
   NHGIS code:  ACI
 
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Data Dictionary
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Context Fields 
    GISJOIN:     GIS Join Match Code
    YEAR:        Data File Year
    STATE:       State Name
    STATEA:      State Code
    COUNTY:      County Name
    COUNTYA:     County Code
    AREANAME:    Area name
 
Table 1:     Total Urban Population in Cities of 25,000 and Over
Universe:    Urban Persons in Cities of 25,000 and Over
Source code: NT3
NHGIS code:  ACW
    ACW001:      Total
 
Table 2:     Number of Students by Type of Learning Institutions
Universe:    Students
Source code: NT14
NHGIS code:  ACI
    ACI001:      Universities or colleges
    ACI002:      Academies and grammar schools
    ACI003:      Primary and common schools
 
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Citation and Use of NHGIS Data
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All persons are granted a limited license to use this documentation and the
accompanying data, subject to the following conditions:

* Publications and research reports employing NHGIS data (either tabular or GIS)
  must cite it appropriately. The citation should include the following:

    Minnesota Population Center. National Historical Geographic Information
    System: Version 2.0. Minneapolis, MN: University of Minnesota 2011.

* Publications and research reports employing school attendance areas data
  (either tabular or GIS) must cite it appropriately. The citation should
  include the following:

    The College of William and Mary and the Minnesota Population Center.
    School Attendance Boundary Information System (SABINS): Version 1.0.
    Minneapolis, MN: University of Minnesota 2011.

* If possible, citations should also include the URL for the NHGIS site:

    https://www.nhgis.org/

* If possible, citations involving school attendance areas should also include
  the URL for the SABINS site:

    http://www.sabinsdata.org/

In addition, we request that users send us a copy of any publications, research
reports, or educational material making use of the data or documentation.
Printed matter should be sent to:

    NHGIS
    Minnesota Population Center
    University of Minnesota
    50 Willey Hall
    225 19th Ave S
    Minneapolis, MN 55455

Send electronic material to: nhgis@umn.edu