Our intercensal estimates cover the period from 2010 to 2020 and are originally based on population estimates published by the U.S. Census Bureau. We interpolate a new population estimate for each year, so the series connects to population estimates published in the 2020 decade.
The population data are available for the state of Tennessee, its 95 counties and include three characteristic categories.
- Age
- Race/Hispanic Ethnicity
- Sex
Frequently Asked Questions
While both sets of estimates interpolate annual population figures between census years, the Boyd Center’s version will be periodically revised to align with new population projections and can adapt to base population adjustments. When it is published in the fall of 2024, the Census Bureau’s intercensal product will remain fixed to the April 1, 2020, Census results and no other updates are planned. Moreover, the Boyd Center’s estimates are designed to be connected to the population level on July 1, 2020, as reflected in the latest Census Bureau population estimate vintage.
The Boyd Center’s Intercensal Estimates utilize the U.S. Census Bureau’s Vintage 2020 Population Estimates covering the period from 2010 to 2020. The July 1, 2020, population is initially from the Vintage 2022 Population Estimates but will be revised with future population estimate vintage releases.
These intercensal estimates were initially developed to support the Center’s population projections that are released every two years. At a minimum, they will be updated in conjunction with that product’s update cycle but could be updated annually, especially in the first half of the 2020 decade as significant base population adjustments are expected.
Like the source population estimate data, characteristics data are available for three areas, including age, race/Hispanic Ethnicity, and sex. With regard to the race groups, there is one important modification. Specifically, the “non-Hispanic other races” category combines four race groups published in the Census Bureau estimates: American Indian and Alaska Native alone, Asian alone, Native Hawaiian and Other Pacific Islander alone, and two or more races.
Overview of the Characteristic Groups for the Boyd Center Intercensal Population Estimates
Age
18 groups |
Race/Hispanic Ethnicity
4 groups |
Sex
2 groups |
- 5-year age groups for residents under 85 years of age
- 1 group for population over 85 years and over.
|
- Non-Hispanic White alone
- Non-Hispanic Black alone
- Non-Hispanic other races
- Hispanic or Latino
|
|
The July 1, 2020, population from the U.S. Census Bureau Vintage 2022 Population Estimates serves as the endpoint for the Boyd Center Intercensal Estimates. The Boyd Center plans to adjust this endpoint in support of future population projection updates to align with future Census Bureau estimate vintages that incorporate additional base population revisions.
Once intercensal estimates are available, they become the preferred population series for the decade. For example, after its fall 2024 publication, the U.S. Census Bureau’s intercensal series will become the Census Bureau’s official annual estimate of population for July 1 from 2010 to 2020 and will supersede all other vintages published throughout the decade. The Boyd Center’s intercensal estimates are not an official product, but serve other important purposes related to their use in denominators, growth rates and projections.
The Census Bureau provides guidance for data users that includes additional information on this topic.
The Boyd Center Intercensal Estimates cover the period from July 1, 2010, to July 1, 2020. The value for July 1, 2010 is based on U.S. Census Bureau estimates published in the Vintage 2020 evaluation estimates. The value for July 1, 2020, is presently connected to the Vintage 2022 County Population by Characteristics that were published in June 2023, but will be updated to reflect the numbers shown in future vintages.
For 2011 to 2019, annual population figures are interpolated to correct the error of closure between Vintage 2020 and Vintage 2022 estimate at July 1, 2020. In most cases, the error of closure is distributed linearly across the entire decade.
The Census Bureau’s intercensal estimates remained fixed to the April 1, 2020 Census results. The 2020 Census data also served as the base population for the next decade’s population estimates. However, this decade the Bureau adopted a new methodology which incorporates additional data and methodological improvements that address delays in obtaining detailed 2020 Census data and related quality concerns.
This new “Blended Base” approach means that the July 1, 2020, population published in this decade’s postcensal population estimate vintages will likely change in terms of population and characteristic makeup.
Multidecade population series: The estimates should connect to the U.S. Census Bureau’s 2000-2010 population projections as well as the most current vintage population estimates for the 2020s.
Denominators: Per capita calculations and other rates of incidence tied to state or county characteristics including age, race, Hispanic ethnicity and sex
These annual estimates were interpolated using a formula developed by Census Bureau mathematician Prithwis Das Gupta. For 2000-2010, the Bureau employed Das Gupta’s Method 6 to correct the error of closure. For 2020, the agency is expected to switch to Das Gupta Method 2. In this approach, the correction applied to each figure is directly proportional to the time elapsed since July 1, 2010, and the correction increases arithmetically over time.
More details about both formulas and exceptions where linear interpolation cannot be used are found in our technical documentation.
If you have other questions, be sure to drop us a line at tnsdc@utk.edu or call (865) 974-6070.
