Documentation
Data Sources
This product uses county-level data from the U.S. Department of Commerce, Bureau of the Census, 1960, 1970, 1980, 1990, and 2000 Decennial Censuses and American Community Survey (ACS) 5-year period estimates for 2007–11, 2015–19, and 2017–21. Data for census tracts include the same data sources and years except for 1960 (because of the limited number of defined census tracts in that year of data collection) and 2017–21 (an update that will include this data period is anticipated in the summer of 2024). Poverty rates for census tracts in the years before 2007–11 are calculated using data from Geolytics’ Neighborhood Change Database. The Neighborhood Change Database normalizes Decennial Census data to 2010 census-tract geographies allowing for better comparisons of census tract poverty rates over time. USDA, Economic Research Service (ERS) relies on poverty/population counts from these sources to derive poverty rates that are used to create the poverty area measures in this data product.
Metropolitan statistical areas (used in the county-level metro/nonmetro indicators in the data files) are defined by the U.S. Office of Management and Budget and delineation files are published by the U.S. Department of Commerce, Bureau of the Census.
Data Reliability
ACS estimates are derived from a sample of the total U.S. population, which means they are subject to sampling error, particularly for geographic areas with small populations. The U.S. Bureau of the Census publishes a measure of this error, the margin of error (MOE). This information is used to account for the possibility of low data reliability in some geographies. The derived MOE and coefficient of variation (CV) for each poverty rate are generated from the ACS estimates. The CV is used to create a reliability index to classify each observation’s reliability as low, moderate, and high.
Instructions for calculating the margin of error for user-derived proportions and percentages using ACS data can be found in chapter 8 of the ACS General Handbook. Instructions for calculating the coefficient of variation and constructing the reliability index can be found in The American Community Survey ESRI White Paper.
In addition, the derived MOEs of the poverty rate estimates are used to determine the upper and lower bounds of the confidence interval for each poverty rate estimate (poverty rate +/- MOE). This information is used to determine if an area’s high (poverty rate of 20 percent or more) or extreme (poverty rate of 40 percent or more) poverty area status would change at its upper or lower bound values.
High and extreme poverty area status are not reported for geographic areas with a low reliability index score (CV greater than 40 percent) and where the upper and lower bound values of its confidence interval would change the poverty area status determined by the estimate. These areas are coded as "not available" with a coded value of –1 in the poverty area measures data file. This applies to ACS data years only; measures of reliability are not determined for Decennial Census data years. However, the same coding is used for high and extreme poverty area measures where count data for determining the poverty rate are missing in any data period for Decennial Census or ACS.
Persistent poverty area (high poverty for 4 consecutive time periods spanning 30 years) and enduring poverty area (high poverty for at least 5 consecutive time periods spanning approximately 40 years or more) measures are not reported (also coded as –1 in the data file) if high poverty status is coded as "not available" in any of the data years included in the measure’s formula.
Geographic Coverage
The geographic coverage of this data product is currently limited to counties and census tracts within the 50 States and Washington DC due to data limitations for earlier years as well as concerns about the appropriateness of applying the poverty thresholds to areas with markedly different economic conditions. Poverty count data may be missing in any given year, but this is more likely for counties in 1960 and for census tracts in the years 1960, 1970, and 1980. No measures are reported for 1960s census tracts given that census tract geography at that time was extremely limited. Census tract geography improved over time but was not available nationwide until 1990.
| Data period | Counties where poverty status is determined (out of a total possible 3,142) | Census tracts where poverty status is determined (out of a total possible 73,057) | ||
|---|---|---|---|---|
| High poverty | Extreme poverty | High poverty | Extreme poverty | |
| 1960 | 3,110 | 3,110 | NA | NA |
| 1970 | 3,117 | 3,117 | 51,923 | 51,923 |
| 1980 | 3,127 | 3,127 | 58,608 | 58,608 |
| 1990 | 3,133 | 3,133 | 72,629 | 72,629 |
| 2000 | 3,136 | 3,136 | 72,840 | 72,840 |
| 2007–11 | 3,136 | 3,141 | 69,789 | 71,615 |
| 2015–19 | 3,135 | 3,142 | 71,066 | 71,989 |
| 2017–21 | 3,132 | 3,140 | NA | NA |
| NA = Not available. Census tracts are unavailable for 1960; the 2017–21 data period is not currently included. Note: Geographic coverage is currently limited to counties and census tracts within the 50 States and Washington DC. High poverty and extreme poverty areas are as determined in the December 2023 release of the USDA, ERS poverty area measures data product. Source: USDA, ERS using data from the U.S. Department of Commerce, Bureau of the Census, 1960, 1970, 1980, 1990, and 2000 Decennial Census data and 2007–11, 2015–19, and 2017–21 American Community Survey 5-year estimates. |
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| Data period | Counties where poverty status is determined (out of a total possible 3,142) | Census tracts where poverty status is determined (out of a total possible 73,057) | ||
|---|---|---|---|---|
| Persistent poverty | Enduring poverty | Persistent poverty | Enduring poverty | |
| Ending in 1990 | 3,109 | NA | NA | NA |
| Ending in 2000 | 3,117 | NA | 51,801 | NA |
| Ending in 2007–11 | 3,121 | 3,111 | 55,952 | 49,508 |
| Ending in 2015–19 | 3,123 | 3,117 | 68,625 | 55,161 |
| Ending in 2017–21 | 3,119 | 3,113 | NA | NA |
| NA = Not available. Census tracts are unavailable for 1960; the 2017–21 data period is not currently included. Note: Geographic coverage is currently limited to counties and census tracts within the 50 States and Washington DC. High poverty and extreme poverty areas are as determined in the December 2023 release of the USDA, ERS poverty area measures data product. Source: USDA, ERS using data from the U.S. Department of Commerce, Bureau of the Census, 1960, 1970, 1980, 1990, and 2000 Decennial Census data and 2007–11, 2015–19, and 2017–21 American Community Survey 5-year estimates. |
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Geographic Normalization
All census tract poverty area measures are reported using 2010 census tract geography (see Data Sources above). This consistency allows researchers to directly compare census tract measures over time. All county poverty area measures are reported using current county geography up until 2020. Any changes in county geocoding are applied to the census tract geocoding. For example, between 2010 and 2020, Shannon County, South Dakota was renamed Oglala Lakota and was assigned a new county Federal Information Processing Standards (FIPS) code. The geographic identifiers for all census tracts within the county were updated to reflect the new FIPS code. This geographic normalization process accounts for any differences between the census tract and county geocoding, which allows for direct comparison of the two geographic scales in any year included in the poverty area measures data file.
Updates Revision History
December 8, 2023—An update to the data product included county-level measures for 2017–21.
November 10, 2022—The initial Poverty Area Measures data product was released in November 2022 and covered the period 1960 through 2015–19.
Additional Details
The downloadable Excel data file includes separate worksheets for county and census tract measures as well as a worksheet with combined county and census tract measures. Geocoding is provided for merging any of the data sheets with supplemental data that use similar U.S. Department of Commerce, Bureau of the Census’s geographies. The Excel workbook also includes worksheets with documentation and a poverty area measures codebook, which can be referenced for more detailed information.
Recommended Citation
U.S. Department of Agriculture, Economic Research Service. Poverty Area Measures, December 2023.