Data and Methods: 2010-2020
These data include estimates of net migration for US counties by five-year age group, sex, and various race categories each decade from the 1950s through the 2010s. The 1990s, 2000s, and 2010s also include estimates by Hispanic origin, and the 2010s include estimates for American Indians/Alaskan Natives and for non-Hispanic Asian/Pacific Islanders. Estimates for Hispanics in the 2010s are not currently included and will be added in the coming months.
What is net migration?
Net migration is the balance of in-migrants minus out-migrants. The data do not include flows of in-migrants or out-migrants. Instead, these data include only the net balance. For each age group, age refers to age at the end of the decade.
Where do the data come from?
Estimates were generated using a residual method based on adjusted US Census counts at the beginning and end of each decade and intercensal birth and death records. The population counted at the beginning of the decade is aged forward over time, subtracting out deaths and adding in births, to generate an "expected population" at the end of the decade. This expected population is then subtracted from the observed population at the end of the decade to estimate the number of net migrants. Net migration estimates were generated following this general process each decade by different research teams to create a coherent dataset spanning 70 years of age-specific net migration for US counties (see References below). Learn more about this method by reviewing our Detailed Documentation for the 2010s or with this Working Paper.
How accurate are the data?
Because the estimates do not rely on sampling, they are highly accurate and reliable. Still, there are some limitations that users should consider. Estimates are less accurate for children under age 10, because birth records are occasionally misrecorded to the wrong county of residence. Estimates may also be less accurate at the oldest ages, due to challenges associated with death records. Breakdowns by race/ethnicity are less accurate than totals because of differences in how race/ethnic categories are recorded in birth records, death records, the decennial census, and the Population Estimates Program and changes over time. These challenges are particularly true for the youngest and oldest age groups which are more dependent on birth and death records, and most significantly impact the American Indian/Alaska Native (AIAN) population. Given these challenges to data accuracy, net migration estimates for AIAN under age 10 are suppressed. Estimates for any cell (group) with an expected population less than 10 are also suppressed.
Data versions: 2010s
For the 2010-2020 decade, the delayed release of Census 2020 detailed results led the U.S. Census Bureau's Population Estimates Program to experiment with new methods of creating a "blended base" in the years following Census 2020. The net migration estimates presented here rely on this base as the final population at the end of the decade. The methods for constructing this base changed from vintage 2021 to vintage 2022 and vintage 2023. We released initial "beta" net migration estimates on this site in April 2023 using the vintage 2021 base. We updated the net migration estimates and released an improved version in July 2024 using the vintage 2022 base. This means that any charts, maps, or data downloads made from this website for the 2010-2020 net migration estimates prior to July 26, 2024 should be revised with the updated data.
The Census Bureau made further improvements to the base for the Hispanic population with the vintage 2023 release. For this reason, net migration estimates for the Hispanic population are not included on this website with the July 2024 release and are expected for release in late 2024.
Data from all decades are available for download via the Data Download tab or at ICPSR.
Video: How To Interpret Net Migration Charts by Age for Counties
Resources
- Population Reference Bureau (PRB): Webinar: Net Migration Patterns as a Tool to Understand Community Change
- ICPSR: Data Archive
- USDA Economic Research Service (ERS): Atlas of Rural and Small Town America
- Internal Revenue Service (IRS): County to County Migration Flows Data
- US Census Bureau: data.census.gov
- US Census Bureau: Census Flows Mapper
References
1950s: Bowles, G. K. and J. D. Tarver. 1965. Net Migration of the Population, 1950-60, by Age, Sex and Color. Washington, D.C.: U.S. Department of Agriculture, Economic Research Service.
1960s: Bowles, G. K., C. L. Beale, and E. S. Lee. 1975. Net Migration of the Population,1960-70, by Age, Sex and Color. Washington: U.S. Department of Agriculture, Economic Research Service and Athens: University of Georgia.
1970s: White, M. J., P. Mueser, and J. P. Tierney.1987. Net migration of the population of the United States 1970-80, by age, race and sex. (Computer file with documentation.) Ann Arbor, MI: Inter-university Consortium for Political and Social Research.
1980s: Fuguitt, G. V., C. L. Beale, and P. R. Voss. 2010. County-Specific Net Migration Estimates, 1980-1990. ICPSR26761-v1. Ann Arbor, MI: Inter-university Consortium for Political and Social Research, 2010-04-02. doi:10.3886/ICPSR26761
1990s: Voss, P. R., S. McNiven, R. B. Hammer, K. M. Johnson, G. V. Fuguitt. 2004. County-specific net migration by five-year age groups, Hispanic origin, race and sex 1990-2000. CDE Working Paper No. 2004-24. Center for Demography and Ecology, University of Wisconsin-Madison. Madison, WI.
2000s: Winkler, R.L., K. M. Johnson, C. Cheng, P.R. Voss, and K.J. Curtis. 2013. County-specific net migration by five-year age groups, Hispanic origin, race and sex 2000-2010. CDE Working Paper No. 2013-04. Center for Demography and Ecology, University of Wisconsin-Madison. Madison, WI.
2010s: Egan-Robertson, David, Katherine J. Curtis, Richelle L. Winkler, and Kenneth M. Johnson, Age-Specific Net Migration Estimates for US Counties, 2010-2020.