Website alows the public full access to the 1940 Census images, census maps and descriptions.

Abstract

The Integrated Public Use Microdata Series (IPUMS) Complete Count Data include more than 650 million individual-level and 7.5 million household-level records. The microdata are the result of collaboration between IPUMS and the nation’s two largest genealogical organizations—Ancestry.com and FamilySearch—and provides the largest and richest source of individual level and household data.

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Documentation

Historic data are scarce and often only exists in aggregate tables. The key advantage of historic US census data is the availability of individual and household level characteristics that researchers can tabulate in ways that benefits their specific research questions. The data contain demographic variables, economic variables, migration variables and family variables. Within households, it is possible to create relational data as all relations between household members are known. For example, having data on the mother and her children in a household enables researchers to calculate the mother’s age at birth. Another advantage of the Complete Count data is the possibility to follow individuals over time using a historical identifier.

In sum: the historic US census data are a unique source for research on social and economic change and can provide population health researchers with information about social and economic determinants.

The historic US 1920 census data was collected in January 1920. Enumerators collected data traveling to households and counting the residents who regularly slept at the household. Individuals lacking permanent housing were counted as residents of the place where they were when the data was collected. Household members absent on the day of data collected were either listed to the household with the help of other household members or were scheduled for the last census subdivision.

Notes

• We provide household and person data separately so that it is convenient to explore the descriptive statistics on each level. In order to obtain a full dataset, merge the household and person on the variables SERIAL and SERIALP. In order to create a longitudinal dataset, merge datasets on the variable HISTID.

• Households with more than 60 people in the original data were broken up for processing purposes. Every person in the large households are considered to be in their own household. The original large households can be identified using the variable SPLIT, reconstructed using the variable SPLITHID, and the original count is found in the variable SPLITNUM.

• Coded variables derived from string variables are still in progress. These variables include: occupation and industry.

• Missing observations have been allocated and some inconsistencies have been edited for the following variables: SPEAKENG, YRIMMIG, CITIZEN, AGE, BPL, MBPL, FBPL, LIT, SCHOOL, OWNERSHP, MORTGAGE, FARM, CLASSWKR, OCC1950, IND1950, MARST, RACE, SEX, RELATE, MTONGUE. The flag variables indicating an allocated observation for the associated variables can be included in your extract by clicking the ‘Select data quality flags’ box on the extract summary page.

• Most inconsistent information was not edited for this release, thus there are observations outside of the universe for some variables. In particular, the variables GQ, and GQTYPE have known inconsistencies and will be improved with the next release.

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Section 2

This dataset was created on 2020-01-10 18:46:34.647 by merging multiple datasets together. The source datasets for this version were:

IPUMS 1920 households: This dataset includes all households from the 1920 US census.

IPUMS 1920 persons: This dataset includes all individuals from the 1920 US census.

IPUMS 1920 Lookup: This dataset includes variable names, variable labels, variable values, and corresponding variable value labels for the IPUMS 1920 datasets.

The Bureau of the Census has released Census 2000 Summary File 1 (SF1) 100-Percent data. The file includes the following population items: sex, age, race, Hispanic or Latino origin, household relationship, and household and family characteristics. Housing items include occupancy status and tenure (whether the unit is owner or renter occupied). SF1 does not include information on incomes, poverty status, overcrowded housing or age of housing. These topics will be covered in Summary File 3. Data are available for states, counties, county subdivisions, places, census tracts, block groups, and, where applicable, American Indian and Alaskan Native Areas and Hawaiian Home Lands. The SF1 data are available on the Bureau's web site and may be retrieved from American FactFinder as tables, lists, or maps. Users may also download a set of compressed ASCII files for each state via the Bureau's FTP server. There are over 8000 data items available for each geographic area. The full listing of these data items is available here as a downloadable compressed data base file named TABLES.ZIP. The uncompressed is in FoxPro data base file (dbf) format and may be imported to ACCESS, EXCEL, and other software formats. While all of this information is useful, the Office of Community Planning and Development has downloaded selected information for all states and areas and is making this information available on the CPD web pages. The tables and data items selected are those items used in the CDBG and HOME allocation formulas plus topics most pertinent to the Comprehensive Housing Affordability Strategy (CHAS), the Consolidated Plan, and similar overall economic and community development plans. The information is contained in five compressed (zipped) dbf tables for each state. When uncompressed the tables are ready for use with FoxPro and they can be imported into ACCESS, EXCEL, and other spreadsheet, GIS and database software. The data are at the block group summary level. The first two characters of the file name are the state abbreviation. The next two letters are BG for block group. Each record is labeled with the code and name of the city and county in which it is located so that the data can be summarized to higher-level geography. The last part of the file name describes the contents . The GEO file contains standard Census Bureau geographic identifiers for each block group, such as the metropolitan area code and congressional district code. The only data included in this table is total population and total housing units. POP1 and POP2 contain selected population variables and selected housing items are in the HU file. The MA05 table data is only for use by State CDBG grantees for the reporting of the racial composition of beneficiaries of Area Benefit activities. The complete package for a state consists of the dictionary file named TABLES, and the five data files for the state. The logical record number (LOGRECNO) links the records across tables.

The 1950 Census population schedules were created by the Bureau of the Census in an attempt to enumerate every person living in the United States on April 1, 1950, although some persons were missed. The 1950 census population schedules were digitized by the National Archives and Records Administration (NARA) and released publicly on April 1, 2022. The 1950 Census enumeration district maps contain maps of counties, cities, and other minor civil divisions that show enumeration districts, census tracts, and related boundaries and numbers used for each census. The coverage is nation wide and includes territorial areas. The 1950 Census enumeration district descriptions contain written descriptions of census districts, subdivisions, and enumeration districts.

Archive of 1981 census aggregate data for England, Wales and Scotland, as made available originally on the Casweb (https://casweb.ukdataservice.ac.uk) platform.

Analysis unit

Persons, households, and dwellings

UNITS IDENTIFIED: - Dwellings: yes - Vacant Units: no - Households: yes - Individuals: yes - Group quarters: yes

UNIT DESCRIPTIONS: - Dwellings: A separate inhabited tenement, containing one or more families under one roof. Where several tenements are in one block, with walls either of brick or wood to divide them, having separate entrances, they are each to be numbered as separate houses; but where not so divided, they are to be numbered as one house. - Households: One person living separately in a house, or a part of a house, and providing for him or herself, or several persons living together in a house, or in part of a house, upon one common means of support, and separately from others in similar circumstances - Group quarters: Yes

Universe

All persons living in the United States including temporarily absent residents and sailors at sea, no matter how long they may have been absent, if they were believed to be still alive. "Indians not taxed", which refers to Native Americans living on reservations or under tribal rule. Native Americans who had renounced tribal rule and "exercise the rights of citizens" were to be enumerated.

Kind of data

Population and Housing Census [hh/popcen]

Sampling procedure

MICRODATA SOURCE: Department of the Interior

SAMPLE SIZE (person records): 273596.

SAMPLE DESIGN: 1-in-100 national random sample of the free population. African-American slaves are not included in this dataset. Individual-level data on the 1860 slave population is available at the

Mode of data collection

Face-to-face [f2f]

Research instrument

The census operation involved six forms. Form 1 was used to enumerate free persons and collected information on individual characteristics. Form 2 was used to enumerate slaves. Other forms were used to record information about agriculture and industry.

This dataset includes all individuals from the 1920 US census.

This dataset includes all households from the 1940 US census.

1828 Census: Alphabetical return
This is the first census ever to be taken in Australia and the most complete one extant. It records both convicts and free persons but does not include serving military personnel and their families. (1)

The 1828 Census was compiled in six volumes [SZ978-983]. In all but the first volume the title is given as ‘New South Wales Census, taken in the Month of November 1828’.

It is a list in alphabetical order by surname compiled from the census returns for individual householders and government establishments. Each individual has been allocated a running number within his or her letter of the alphabet. Family groups living at the same household are listed together.

Beside running number and name the list records age, free or bond, ship, year, sentence, religion, employment, residence, district, total number of acres, acres cleared, acres cultivated, horses, horned cattle, sheep, remarks.

Inside the cover of the first volume [SZ978] there is a typescript note dated 13 July 1932 and signed by F.M. O’Donohue, Acting Registrar General:

‘These books were handed to Mr Hayce-Williams [sic] by Mr Fosbery, when the latter was retiring from the position of Inspector General of Police. Mr Hayes-Williams told me that they were given over to him on his promise to use the utmost care to see that their contents were not divulged.

‘It will be noticed that entries 1 to 91 are missing. Mr H.J. Rumsey a few weeks ago gave me the loose sheets herein and stated that he had obtained them from the Home Office in London where a copy of the 1828 Census is filed.’

Herbert John Rumsey was the first President of the Society of Australian Genealogists, founded in 1932. (2) He had obtained copies from London from the copy despatched to the Home Office of the 1828 Census now held at The National Archives of the United Kingdom as HO 10/21 to 10/27. (3)

Abbreviations and later inclusions
Abbreviations used in the column ‘Free or Bond’ were specified in the printed ‘Instructions for filling up the Returns for the Census of the Year 1828’ dated 1 September 1828:

B.C. for Born in the Colony.
C.F. for Came Free.
F.S. for Free by Servitude.
A.P. for Holding an Absolute Pardon.
C.P. for Holding a Ticket of Leave.
C. for Convict.
C.S. for Colonial Sentence.
G.S. for Government (or Assigned) Servant. (4)

A list of abbreviations dated 16 April 1931 is also included inside the cover of the first volume.

At the end of the first volume [SZ978] a ‘Report on European Archives, by Mr F.M. Bladen, Barrister-at-Law, printed 26 August 1903 for the Parliament of the Commonwealth of Australia is included. A newscutting from the Sydney Morning Herald, 16 July 1932 relating to Thomas Kendall is pasted into the third volume [SZ980] near his entry.

Background
On 30 June 1828 the New South Wales Legislative Council passed ‘An Act for ascertaining the Number Names and Condition of the Inhabitants of the Colony of New South Wales and also the Number of Cattle and the Quantity of located cleared and cultivated Land within the said Colony’, known as the Census Act of 1828 (9 Geo. IV No.5). Magistrates were to affix notices in conspicuous places in their districts ‘requiring every householder employer of servants owner or possessor of cattle proprietor or occupier of land’ to answer questions relating to the population and land and stock of the Colony. (5)

The Act also provided that in the case of refusal or neglect to answer these questions or the giving of false or untrue answers the Magistrates were able to impose a fine not exceeding Ten Pounds. (6)

Printed ‘Instructions for filling up the Returns for the Census of the Year 1828’ dated 1 September 1828 were issued by the Colonial Secretary, Alexander McLeay, to the Magistrates together with a circular dated 18 September 1828 specifying the use of printed forms in the taking of the ‘General Census of the Colony’. (7)

Previously Government and General Orders had required convicts to attend a muster to be counted at a specified place on a specific day. (8) For the taking of the census the approach was for constables or other suitable census takers to visit the householders’ properties with the printed forms provided. No date was specified in the Act for the taking of the census but the Magistrates and others were urged to complete their districts as soon as practicable.

The earliest returns were received by the Colonial Secretary on 8 November 1828 from Wallis Plains, followed on 20 November by those for Newcastle. (9) In most areas the returns were completed in November 1828, though some areas took longer to submit them to the Colonial Secretary. Amended returns were received as late as November 1829. (10) A circular to Magistrates dated 29 September 1829 required the Magistrates to confirm the correctness of the Census for their area with the last confirmation received on 17 December 1829. (11)

The householders’ forms (NRS 1273) were returned by the Magistrates to the Colonial Secretary. The clerks in the Colonial Secretary’s Office then compiled a district abstract (NRS 1274) for each district and statistics for government establishments. Summary statistics were compiled of population and land and stock for each district. An Abstract of the population of the Colony of New South Wales, and of the Land and Livestock held therein was also prepared. These statistics were first published in the Sydney Gazette on 26 September 1829. (12)

It is not known when the compilation of the six volumes was completed. In October 1828 the Colonial Secretary Alexander McLeay wrote that ‘it is hoped that when the Returns are abstracted, and the names classed alphabetically, the danger of double entries and omisions will be equally obviated’. (13)

Subsequent history
The volumes of the 1828 Census passed into the possession of the Inspector General of Police. In 1901 the Inspector General made a submission to the Chief Secretary that these records should be placed in the care of the Registrar General. The matter was considered by a committee appointed by the Premier and Chief Secretary. This committee consisted of the Principal Under Secretary of the Premier’s Department (Mr R.C. Critchet Walker), the Inspector General of Police (Mr Edmund Fosbery) and the Registrar General (Mr William Gordon Hayes Williams). It recommended that the records of the 1828 Census be placed in the care of the Registrar General to be kept under lock and key, the Registrar General himself retaining the key. (14) The volumes, along with the case which housed them and its key, were transferred as State archives on 25 March 1965. (15)

UNESCO Australian Memory of the World Register
The records of the 1828 Census were inscribed on the UNESCO Australian Memory of the World Register on 27 February 2019.

Endnotes
1. Census of New South Wales – November 1828, Edited by Malcolm R Sainty & Keith A Johnson. Sydney: Library of Australian History, 1980 and subsequently published, with additional information, on CD-ROM 2001 and Revised Edition 2008, Introduction (PDF) ‘Census of New South Wales November 1828, available from Biographical Database of Australia website, https://www.bda-online.org.au/sources/musters-census/ (accessed 22 February 2019), p.13; NRS 905, Main series of letters received [Colonial Secretary], 1828 [4/2007.2].
2. K. A. Johnson, 'Rumsey, Herbert John (1866–1956)', Australian Dictionary of Biography, National Centre of Biography, Australian National University, http://adb.anu.edu.au/biography/rumsey-herbert-john-8297/text14543, published first in hardcopy 1988, accessed online 22 February 2019. This article was first published in hardcopy in Australian Dictionary of Biography, Volume 11, (MUP), 1988.
3. TNA (UK): HO Home Office: Settlers and Convicts, New South Wales and Tasmania: Records., HO 10/21 to HO 10/27, http://discovery.nationalarchives.gov.uk/browse/r/h/C1905858 (accessed 22 February 2019). The Home Office volumes, while including most of the same details, are not identical to the 1828 Census: Alphabetical registers.
4. Instructions of 1 September 1828 in NRS 906, Special bundles [Colonial Secretary], 1826: Census of 1828 – instructions, circulars, and samples of forms to be used [4/1097].
5. Census of 1828 (9 Geo. IV No.5).
6. Ibid.
7. Instructions of 1 September 1828 and Circular, 18 September 1828 in NRS 906, Special bundles [Colonial Secretary], 1826: Census of 1828 – instructions, circulars, and samples of forms to be used [4/1097].
8. For example see Historical Records of Australia Series I, Vol. I, p.678.
9. Colonial Secretary; NRS 922, Registers of letters received, 1828 [5/2342] Reel 2929, q.v. Nos. 28/8991 and 28/9341.
10. Ibid., q.v. Nos. 29/6673 and 29/8653.
11. Ibid., q.v. Nos. 29/8147; NRS 905, Main series of letters received, 1828 Letter No.29/9898 in [4/2056].
12. Sydney Gazette and New South Wales Advertiser, 26 September 1829, p.1, https://trove.nla.gov.au/newspaper/article/2193488 (accessed 21 February 2019).
13. NRS 989, Copies of letters to Magistrates, Police etc, 17 October 1828, Out Letter 38/741 [4/3826] pp.493-494, Reel 2807.
14. Archives Authority of New South Wales, Disposal Recommendation (DR631).
15. AO File 65/0120 and

This dataset includes variable names, variable labels, variable values, and corresponding variable value labels for the IPUMS 1920 datasets.

The US government's 'Topologically Integrated Geographic Encoding and Referencing' system, usually referred to as TIGER, is based on an extensive database of US geographic information. It is county-level data that documents physical features like roads and rivers, as well as some administrative features such as Congressional districts. Data can be downloaded for each state and for each of the following: Puerto Rico, American Samoa, Guam, Northern Mariana Islands, Midway Island, and the US Virgin Islands.

The database does not contain demographic or topographic (terrain) data; the "topology" referenced in the name refers to how the database itself is designed.

Only recent versions are available online for free download. Note also that the Census Bureau is making substantial changes to how the TIGER system is formatted, which should allow for wider and more effective compatibility with GIS tools. A good overview can be seen at this page

This file contains the National Statistics Postcode Lookup (NSPL) for the United Kingdom as at August 2022 in Comma Separated Variable (CSV) and ASCII text (TXT) formats. To download the zip file click the Download button. The NSPL relates both current and terminated postcodes to a range of current statutory geographies via ‘best-fit’ allocation from the 2021 Census Output Areas (national parks and Workplace Zones are exempt from ‘best-fit’ and use ‘exact-fit’ allocations) for England and Wales. Scotland and Northern Ireland has the 2011 Census Output AreasIt supports the production of area based statistics from postcoded data. The NSPL is produced by ONS Geography, who provide geographic support to the Office for National Statistics (ONS) and geographic services used by other organisations. The NSPL is issued quarterly. (File size - 184 MB).

The TIGER/Line shapefiles and related database files (.dbf) are an extract of selected geographic and cartographic information from the U.S. Census Bureau's Master Address File / Topologically Integrated Geographic Encoding and Referencing (MAF/TIGER) Database (MTDB). The MTDB represents a seamless national file with no overlaps or gaps between parts, however, each TIGER/Line shapefile is designed to stand alone as an independent data set, or they can be combined to cover the entire nation. ZIP Code Tabulation Areas (ZCTAs) are approximate area representations of U.S. Postal Service (USPS) ZIP Code service areas that the Census Bureau creates to present statistical data for each decennial census. The Census Bureau delineates ZCTA boundaries for the United States, Puerto Rico, American Samoa, Guam, the Commonwealth of the Northern Mariana Islands, and the U.S. Virgin Islands once each decade following the decennial census. Data users should not use ZCTAs to identify the official USPS ZIP Code for mail delivery. The USPS makes periodic changes to ZIP Codes to support more efficient mail delivery. The Census Bureau uses tabulation blocks as the basis for defining each ZCTA. Tabulation blocks are assigned to a ZCTA based on the most frequently occurring ZIP Code for the addresses contained within that block. The most frequently occurring ZIP Code also becomes the five-digit numeric code of the ZCTA. These codes may contain leading zeros. Blocks that do not contain addresses but are surrounded by a single ZCTA (enclaves) are assigned to the surrounding ZCTA. Because the Census Bureau only uses the most frequently occurring ZIP Code to assign blocks, a ZCTA may not exist for every USPS ZIP Code. Some ZIP Codes may not have a matching ZCTA because too few addresses were associated with the specific ZIP Code or the ZIP Code was not the most frequently occurring ZIP Code within any of the blocks where it exists. The ZCTA boundaries in this release are those delineated following the 2020 Census.

Analysis unit

Persons and households

UNITS IDENTIFIED: - Dwellings: no - Vacant Units: no - Households: yes - Individuals: yes - Group quarters: no

UNIT DESCRIPTIONS: - Dwellings: A building is an independent free-standing structure irrespective of its construction material, composed of one or more rooms. - Households: A household consists of a person or a group of persons who live together in the same housing unit or part of it and who consider themselves as one unit in terms of the provision of food and/or other essentials of living for the group. When most of the members of such a group are related by blood (i.e., biologically) the group shall be referred to as a Private Household for the purpose of the census. On the other hand when the group (i.e., household as defined earlier) consists of members who are not related by blood and they are more than 10, they will be considered as Non-Institutional Collective Household. Note that if the group consists of 10 or less members, it should be considered a private household. - Group quarters: An institution is usually a set of premises used to house a large number of people who are not related by blood or marriage but bound together by a common objective or personal interest (e.g., universities, boarding houses, hospitals, army barracks, camps, prisons, hotels, etc.)

Universe

Residents of South Sudan Homeless, regugees, camp residents. Nomadic population is that group of people who rear cattle or livestock and do not stay in specific areas for long periods of time. They live in mobile housing units, usually made of wood, hide, etc. and are continuously moving in search of water and grazing for their animals. Administratively they are affiliated to tribal 'Sheikhs'and 'Farigs' councils.

Kind of data

Population and Housing Census [hh/popcen]

Sampling procedure

MICRODATA SOURCE: Southern Sudan Centre for Census, Evaluation and Statistics

SAMPLE SIZE (person records): 542765.

SAMPLE DESIGN: Long form questionnaire for sedentary households (selected enumeration areas) and a sample of nomad households. Homeless, regugees, camp residents. Nomadic population is that group of people who rear cattle or livestock and do not stay in specific areas for long periods of time. They live in mobile housing units, usually made of wood, hide, etc. and are continuously moving in search of water and grazing for their animals. Administratively they are affiliated to tribal 'Sheikhs'and 'Farigs' councils.

Mode of data collection

Face-to-face [f2f]

Research instrument

Two forms: Long Questionnaire (for a sample of areas) and Short Questionnaire (for the rest of the country). The information used here is based on the long form questionnaire.

Bee Colony Dynamics

U.S. Survey and Census Data

By Brenda Griffith [source]

About this dataset

This dataset provides access to the rich and expansive bee colony contribution information captured by the United States Department of Agriculture National Agricultural Statistics Service Quick Stats Dataset. Here, you will find survey data by state and census data by county, which can help inform decision-making and research related to beekeeping practices.
Our dataset also covers Bee Informed Partnership's original data on bee colony loss in the U.S., including percentages of colonies exclusive to each state, total winter all loss, number of beekeepers exclusive to each state, as well as overall percentage of populations experiencing losses during a given period. With this valuable data at hand, it becomes easier for policymakers, business owners and researchers to make well informed decisions that help protect our nation's most important pollinators!

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For more datasets, click here.

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How to use the dataset

The first three datasets contain information on colonies and their management while BIP Bee Loss Clean contains information specifically related to bees’ losses during specific periods and years throughout all 50 states. For each dataset there is a “Search Criteria” excel file which provides more details about what data was collected from each set in order for you to better understand it when looking at query results or performing features/dimensionality reduction analyses based on these criteria one might want different levels of aggregation available for his/her use case wherein he can get helpful insights form both state-level as well as county-level granularities wrapped up together into one entity that can help one draw connections between them over time for example . The datasets include fields such as year, period, state code, agricultural district code, watershed code, region and various others related to the characteristics of colonies and their management in different states over multiple years (from 2017–2020). Depending upon your analysis task or outcome you would like perform afterwards you can carefully choose columns/parameters that best serve your purpose accordingly else it would be bear more processing resources than necessary also consequentlly reducing efficiency overall due sacrificing optimal functioning capabilities at least partiually especially regarding system resources being consumed thereby possibly resulting into noteworthy performance degradation overall , quite obviously hence needful for optimal performance & computational efficiencies unique requisites .

You may also look at other similar data collections such as EPA's official Pollutant Release Inventory or PRI dataset which provides pollutant releases(emissions & transfers) along provide additional relevant insights obtained via analysis corresponding pollutants released across varius waetedbodies & farms within US& respective impacts upon ecosystems^ eco services etc etc ..Meanwhile during Mining IT recource consideration should be given particular attention regarding any redundant preprocessing steps if possible execution done

Research Ideas

• Developing an app or device to help beekeepers track their hive health and productivity over time. This could include tracking population of bees, diseases and pests in their hives, and performance in producing honey.
• Analyzing the data to identify geographical regions with the most favorable conditions for successful bee colonies, which can then be used to better inform prospective new beekeepers as well as eager honey consumers looking for ethically sourced honey products.
• Examining how trends in pollen sources available affect beehive production by correlating census data with changes in local flora or climate over time (e.g., studying areas experiencing severe drought vs those with abundant blooming plants)

Acknowledgements

If you use this dataset in your research, please credit the original authors. Data Source

License

License: Dataset copyright by authors - You are free to: - Share - copy and redistribute the material in any medium or format for any purpose, even commercially. - Adapt - remix, transform, and build upon the material for any purpose, even commercially. - You must: - Give appropriate credit - Provide a link to the license, and indicate if changes were made. - ShareAlike - You must distribute your contributions u...

IPUMS-International is an effort to inventory, preserve, harmonize, and disseminate census microdata from around the world. The project has collected the world's largest archive of publicly available census samples. The data are coded and documented consistently across countries and over time to facillitate comparative research. IPUMS-International makes these data available to qualified researchers free of charge through a web dissemination system.

The IPUMS project is a collaboration of the Minnesota Population Center, National Statistical Offices, and international data archives. Major funding is provided by the U.S. National Science Foundation and the Demographic and Behavioral Sciences Branch of the National Institute of Child Health and Human Development. Additional support is provided by the University of Minnesota Office of the Vice President for Research, the Minnesota Population Center, and Sun Microsystems.

The IPUMS National Historical Geographic Information System (NHGIS) provides free online access to summary statistics and GIS files for U.S. censuses and other nationwide surveys from 1790 through the present. NHGIS boundary files are derived primarily from the U.S. Census Bureau's TIGER/Line files with numerous additions to represent historical (1790-1980) boundaries that do not appear in TIGER/Line files. For more recent boundary files (1990 or later), NHGIS typically makes only a few key changes to the TIGER/Line source: (1) we merge files that are available only for individual states or counties to produce new nationwide or statewide files, (2) we project the data into Esri's USA Contiguous Albers Equal Area Conic Projected Coordinate System, (3) add a GISJOIN attribute field, which supplies standard identifiers that correspond to the GISJOIN identifiers in NHGIS data tables, (4) we rename files to use the NHGIS naming style and geographic-level codes, (5) we add NHGIS-specific metadata, and (6) most substantially, we erase coastal water areas to produce polygons that terminate at the U.S. coasts and Great Lakes shores.NHGIS derived this shapefile from the U.S. Census Bureau's 2020 TIGER/Line Shapefiles.