In the middle of the twentieth century, the Bureau of the Budget, in conjunction with the Census Bureau and other federal statistical agencies, introduced a widely used unit of statistical geography, the county-based Standard Metropolitan Area. Metropolitan definitions since then have been generally regarded as comparable, but methodological changes have resulted in comparability issues, particularly among the largest and most complex metro areas. With the 2000 census came an effort to simplify the rules for defining metro areas. This study attempts to gather all available historical geographic and commuting data to apply the current rules for defining metro areas to create comparable statistical geography covering the period from 1940 to 2020. The changes that accompanied the 2000 census also brought a new category, "Micropolitan Statistical Areas," which established a metro hierarchy. This research expands on this approach, using a more elaborate hierarchy based on the size of urban cores. The areas as delineated in this paper provide a consistent set of statistical geography that can be used in a wide variety of applications.
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Finding Suburbia in the Census
June 2025
Working Paper Number:
CES-25-40
This study introduces a methodology that goes beyond the urban/rural dichotomy to classify areas into detailed settlement types: urban cores, suburbs, exurbs, outlying towns, and rural areas. Utilizing a database that provides housing unit estimates for census tracts as defined in 2010 for all decennial census years from 1940 to 2020, this research enables a longitudinal analysis of urban spatial expansion. By maintaining consistent geography across time, the methodology described in this paper emphasizes the era of development, as well as proximity to large urban centers. This broadly applicable methodology provides a framework for comparing the evolution of urban landscapes over a significant historical period, revealing trends in the transformation of territory from rural to urban, as well as associated suburbanization and exurban growth.
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Changes in Metropolitan Area Definition, 1910-2010
February 2021
Working Paper Number:
CES-21-04
The Census Bureau was established as a permanent agency in 1902, as industrialization and urbanization were bringing about rapid changes in American society. The years following the establishment of a permanent Census Bureau saw the first attempts at devising statistical geography for tabulating statistics for large cities and their environs. These efforts faced several challenges owing to the variation in settlement patterns, political organization, and rates of growth across the United States. The 1910 census proved to be a watershed, as the Census Bureau offered a definition of urban places, established the first census tract boundaries for tabulating data within cities, and introduced the first standardized metropolitan area definition. It was not until the middle of the twentieth century, however, the Census Bureau in association with other statistical agencies had established a flexible standard metropolitan definition and a more consistent means of tabulating urban data. Since 1950, the rules for determining the cores and extent of metropolitan areas have been largely regarded as comparable. In the decades that followed, however, a number of rule changes were put into place that accounted for metropolitan complexity in differing ways, and these have been the cause of some confusion. Changes put into effect with the 2000 census represent a consensus of sorts for how to handle these issues.
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Poverty Estimates for Places in the United States
September 2005
Working Paper Number:
CES-05-12
This paper first describes some historical poverty trends, overall and for demographic groups and broad locations within the U.S. from an ongoing household survey, and then presents some specific information on poverty for localities by size, from the most recent decennial census (2000). Rural poverty exceeded urban poverty in 1969 and 1979, but urban poverty in 1999 was higher than rural poverty. Non-metropolitan area poverty exceeded metropolitan area poverty in each of the four censuses, but within each of those areas, rural poverty is now less than urban poverty. Within metropolitan areas, poverty is highest for those in central cities. For urbanized areas (50,000 or more population), the poverty rate is lower as the area gets larger, with the exception of the very largest-sized areas. This higher poverty for the largest places is accounted for entirely by the higher poverty rate for the central city or cities in those urban agglomerations, as the poverty rates for the parts of the urbanized areas not in the central place continue to fall as the area itself gets larger. Some of the critical relationships affecting the poverty rate of places appear to be the location of certain types of people - female householders, non-citizens, people of color, and college graduates.
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Metropolitan Segregation: No Breakthrough in Sight
May 2022
Working Paper Number:
CES-22-14
The 2020 Census offers new information on changes in residential segregation in metropolitan regions across the country as they continue to become more diverse. We take a long view, assessing trends since 1980 and extrapolating to the future. These new data mostly reinforce patterns that were observed a decade ago: high but slowly declining black-white segregation, and less intense but hardly changing segregation of Hispanics and Asians from whites. Enough time has passed since the civil rights era of the 1960s and 1970s to draw this conclusion: segregation will continue to divide Americans well into the 21st Century.
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Locating Hispanic Americans, 1900-2020
July 2025
Working Paper Number:
CES-25-50
This study examines Hispanic Americans' residential settlement patterns nationwide in the last 120 years. Drawing on newly available neighborhood data for the whole country as early as 1900, it documents the direction and timing of changes in two aspects of their location. First, it charts Hispanics' transition from a predominantly rural population to majority metropolitan by 1930 and also their growing presence in all regions of the U.S. while still maintaining a predominance in the West and Texas. Second, it provides the first evidence of the long-term trajectory of their segregation from whites in the metropolitan areas where they were settling. As shown by studies of more recent decades, Hispanics were never as segregated as African Americans. Nonetheless, similar to African Americans, their segregation from whites increased to high levels through the middle of the century, followed by slow decline. For both groups metropolitan segregation was driven mainly by segregation among central city neighborhoods prior to the 1940s. But new forms of segregation ' a growing city/suburb divide and increasing segregation among suburban places ' have become the largest contributors to segregation today.
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The Hidden Costs of Decline: Health Disparities in America's Diminishing Micropolitan Areas
September 2025
Working Paper Number:
CES-25-70
This study examines the relationship between long-term population change and health outcomes in U.S. micropolitan areas, with a focus on life expectancy and mortality disparities. Using a county typology based on the historical population trajectories of micropolitan cores from 1940 to 2020, this analysis reveals that health outcomes are substantially worse in places that experienced sustained decline. These disparities persist even after controlling for demographic and socioeconomic characteristics, suggesting that population loss itself is a key driver of poor public health. Declining micropolitan areas are older, less educated, and report high rates of behavioral risk factors, including smoking, excessive drinking, and physical inactivity. By linking historical demographic trends to tract-level data, this analysis highlights the distinct challenges facing the urban cores of shrinking micropolitan areas. Population decline emerges not only as a demographic trend, but as a marker of structural disadvantage with measurable consequences for community health.
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Urban-Suburban Migration in the United States, 1955-2000
February 2016
Working Paper Number:
CES-16-08
This study uses census microdata from 1960 to 2010 to look at the rates of suburbanization in the 100 largest metro areas. Looking at the racial and ethnic composition of the population, and then further breaking down these groups by income, it's clear that more affluent people were more likely to move to the suburbs. Also, the White non-Hispanic population has long been the most suburbanized group. A majority of the White population lived in suburbs by 1960 in the 100 largest metro areas, while most of the Black non-Hispanic population lived in urban core areas as late as 2000. The Hispanic and Asian populations went from majority urban to majority suburban during this period.
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Design Comparison of LODES and ACS Commuting Data Products
October 2014
Working Paper Number:
CES-14-38
The Census Bureau produces two complementary data products, the American Community Survey (ACS) commuting and workplace data and the Longitudinal Employer-Household Dynamics (LEHD) Origin-Destination Employment Statistics (LODES), which can be used to answer questions about spatial, economic, and demographic questions relating to workplaces and home-to-work flows. The products are complementary in the sense that they measure similar activities but each has important unique characteristics that provide information that the other measure cannot. As a result of questions from data users, the Census Bureau has created this document to highlight the major design differences between these two data products. This report guides users on the relative advantages of each data product for various analyses and helps explain differences that may arise when using the products.2,3
As an overview, these two data products are sourced from different inputs, cover different populations and time periods, are subject to different sets of edits and imputations, are released under different confidentiality protection mechanisms, and are tabulated at different geographic and characteristic levels. As a general rule, the two data products should not be expected to match exactly for arbitrary queries and may differ substantially for some queries.
Within this document, we compare the two data products by the design elements that were deemed most likely to contribute to differences in tabulated data. These elements are: Collection, Coverage, Geographic and Longitudinal Scope, Job Definition and Reference Period, Job and Worker Characteristics, Location Definitions (Workplace and Residence), Completeness of Geographic Information and Edits/Imputations, Geographic Tabulation Levels, Control Totals, Confidentiality Protection and Suppression, and Related
Public-Use Data Products.
An in-depth data analysis'in aggregate or with the microdata'between the two data products will be the subject of a future technical report. The Census Bureau has begun a pilot project to integrate ACS microdata with LEHD administrative data to develop an enhanced frame of employment status, place of work, and commuting. The Census Bureau will publish quality metrics for person match rates, residence and workplace match rates, and commute distance comparisons.
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Structural versus Ethnic Dimensions of Housing Segregation
March 2016
Working Paper Number:
CES-16-22
Racial residential segregation is still very high in many American cities. Some portion of segregation is attributable to socioeconomic differences across racial lines; some portion is caused by purely racial factors, such as preferences about the racial composition of one's neighborhood or discrimination in the housing market. Social scientists have had great difficulty disaggregating segregation into a portion that can be explained by interracial differences in socioeconomic characteristics (what we call structural factors) versus a portion attributable to racial and ethnic factors. What would such a measure look like? In this paper, we draw on a new source of data to develop an innovative structural segregation measure that shows the amount of segregation that would remain if we could assign households to housing units based only on non-racial socioeconomic characteristics. This inquiry provides vital building blocks for the broader enterprise of understanding and remedying housing segregation.
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Access Methods for United States Microdata
August 2007
Working Paper Number:
CES-07-25
Beyond the traditional methods of tabulations and public-use microdata samples, statistical agencies have developed four key alternatives for providing non-government researchers with access to confidential microdata to improve statistical modeling. The first, licensing, allows qualified researchers access to confidential microdata at their own facilities, provided certain security requirements are met. The second, statistical data enclaves, offer qualified researchers restricted access to confidential economic and demographic data at specific agency-controlled locations. Third, statistical agencies can offer remote access, through a computer interface, to the confidential data under automated or manual controls. Fourth, synthetic data developed from the original data but retaining the correlations in the original data have the potential for allowing a wide range of analyses.
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