Known Issues in the U.S. 1790-1840 Complete Count Data

Below is year-specific documentation on some of the issues existing in the 1790-1840 datasets. There are many cases where household-level variables do not match the county totals. Some of the issues will be corrected for the final release, but others are permanent issues in the data. Please email ipums@umn.edu if you find data errors or issues that are not covered in this documentation or if you have any questions.

Household-Level Data Completely or Partially Missing by Year
Year # of Households* States Counties Partial Counties
1790 11,572
1800 3,327
1810 -
1820 6,937 -
1830 14,210 - -
1840 47,796 - - -
*Some households have no data due to illegibility and may appear to have zero people living in them. This number does not include households that are missing due to a lack of data from a particular state or county.
**Washington County, Ohio is the only area available in the Northwest Territory in 1800.
***Van Buren, Michigan is in the data but is only one household and is not identified in Van Buren County.
****These areas in Oxford, Maine are included in the data but not identified because of multiple geography descriptions on enumeration sheets.

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  • Some areas such as Cheshire, New Hampshire did not have all of their data entered from particular sheets so totals will differ from the published data.
  • Dorchester and Montgomery counties in Maryland have additional categories for women and free blacks/mulattos. This means All Other Free Persons and Slaves are incorrectly entered.
  • NOTHFREE and NSLAVE do not match the county totals in some states and should be used with caution.
  • Some county-level records in Tennessee only indicate the total number of persons in the county.

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  • These counties are far short of their published counts because slaves were not recorded:
    South Carolina: Beaufort, Charleston City, Colleton, Georgetown, Orangeburg, Sumter, Chester, Kershaw
    North Carolina: New Hanover
  • NOTHFREE and NSLAVE do not match the county totals in some states. Additionally, NSLAVE is not consistent with the published totals at the national level. Use with caution.
  • Some county-level records in Indiana only indicate the total number of persons in the county.

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  • Wards 7 and 10 in New York City were split up on multiple pages due to the scanning process, meaning these two wards may have cases that are placed in the wrong ward.
  • Manufacturing data was accidentally transcribed as Other Persons or Slaves in the following counties: Stokes Co, NC; Franklin, VT; Windham, VT. These cases have been identified and need to be corrected.
  • The city of Lynn, Massachusetts cannot specify whether cases are within city or outside the city.
  • NOTHFREE and NSLAVE are not consistent with the published figures at the national level and should be used with caution.

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  • NCHILD, NMALE, and NFEMALE are available for this year, but users should be aware that because "Other Free Persons Except Indians Not Taxed" is available for this year, the numbers are not 100% accurate. Since Other Free Persons is such a small proportion of the population at large, we opted to include this variable for 1820.
  • The original data suggested that some of the forms located in Franklin Co, TN likely did not belong there based on the published counts. There was no geography information on the incorrectly placed sheets, but assuming the sheets for this unknown county are complete, the most likely match is Lawrence Co, TN. These records were placed in Lawrence Co, TN for the preliminary release.
  • There are 2,144 households with more individuals employed in an industry than there are in the household. These cases have been flagged.
  • Foreigner, Industry, Slave, and Free Black counts are not consistent with the published totals at the national and state level and should be used with caution.

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  • In Newburyport, MA, the enumerator entered two names for the head of the families on several occasions. Ancestry entered these as two distinct households, leading to duplicate households.
  • Miller County, AK was dissolved and became part of Texas, and a new county named Miller was created in the 1870s. While the two counties are not the exact same area, the two overlap. For now, the county codes are the same.
  • Female Slaves <10 and Disability counts are not consistent with the published figures at the national level. Further, Slave, Disability, Foreigner, and Free Black counts do not match the county totals at the state level. Use with caution.
  • Some counties in Florida have no county-level data available.

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  • Montgomery County, Maryland had the original enumeration as well as copies of the original enumeration that in some cases were alphabetized. While the final counts for the county in both are very close, the household structures often do not match. For the preliminary data, we opted to use what appeared to be the original enumeration, not the final copies.
  • Oceana and Ottawa Counties in Michigan were combined on 4 sheets, so households may not be assigned the correct county. The total population for these two counties was 496 and 208 people respectively.
  • There are 10,623 households with more individuals employed in an industry than there are in the household.
  • In Hagerstown, MD and Natchez City, MS, outlying areas cannot be differentiated from the city limits, so the city population in the Ancestry data does not match the published figures.
  • VETAGE has not been cleaned, and there are several hundred cases that are likely bad transcriptions or incorrect information reported by enumerators.
  • NLIT has not been cleaned. Sometimes, the enumerators recorded this number for the household, and other times, it was recorded for the school. There are also a few cases where the numbers that were "brought forward" for easier counting by census clerks was mistakenly entered, leading to large numbers that are inaccurate.
  • Woburn, MA was not identified as a city in the county-level data, but in our preliminary pass, it met the 2,500 person threshold. This has been coded as a city but has no population in the CITYPOP field.
  • Female Slaves <10, Disability, Ocean/River, and School counts do not match the county totals at the state level. Additionally, Female Slaves <10, Disability, Ocean, School, and Veteran counts are not consistent with the published figures at the national level.