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Projections

Learn more about how Projection file data is collected and processed.

Overview

Population projections estimate populations at future dates. For example, with population projections, we can answer the following questions:

  • How many people will live in a given state in 2024?
  • How many African American people will live in a given county in 2026?
  • How many Non-Hispanic White people will live in a given Census Block in 2030?

Population projections can be calculated at different geographic levels, for different racial or ethnic groups, projected out for any number of years. Population projections are used not only in redistricting, but for academic research and for planning purposes across a variety of sectors.

Why this is important

State-level projections can be used to predict the reapportionment of House of Representatives seats. Census Block-level projections, which are more granular, can be used to measure the impact of a proposed redistricting plan over a ten-year period. Another potential use of Census Block-level population projections is in drawing districts that minimize demographic and total population changes between districts over a ten year period.

For example, with Census Block-level projections, if we have a proposed redistricting plan, we can answer the following questions:

  • What will the racial or ethnic makeup of the districts be in five years?
  • Will the racial or ethnic makeup of the districts remain uniform over the course of the decade?

Additionally, population projections may be useful for planning purposes in redistricting. Community groups and individuals can utilize projections to make sure their community is represented, especially in the case of a delay in the release of U.S. Census P.L. 94-171 redistricting data.

Who is included?

Projections used in redistricting include all residents of the U.S., and often rely on U.S. Census data as a basis for projecting populations. Projections from different sources can vary depending on what assumptions were made about the future. Demographers make assumptions based on existing evidence and then revise their assumptions as new information becomes available. Their sources may include the U.S. Census, the American Community Survey, immigration statistics, and other demographic surveys.

How are projections produced?

Projections illustrate possible courses of population change based on assumptions about future births, deaths, net international migration, and domestic migration in any given geography. They rely on current or historical demographic data as the starting point from which to project future populations.

One source of population projections are those produced by the U.S. Census Bureau. They project the resident population of the U.S. using a cohort-component method and assumptions about demographic components of change (future trends in births, deaths, and net international migration). Download this PDF to read more about the cohort-component method. Note that the U.S. Census Bureau only offers projections at a national level, and not at the state level, or a smaller geographic level.

It is worth highlighting that projections are only forecasts of the future, and should be treated as such. That is, we expect a certain degree of inaccuracy in their predictions, especially for smaller areas of geography and smaller populations of individuals. Users of population projections should keep the limitations of the projections in mind.

Where can this data be found on the Redistricting Data Hub website?

The projections available on Redistricting Data Hub were purchased from HaystaqDNA. They are available at the Census Block level, for Census race categories, and are projected until 2030. These can be found for each state on their respective data download pages, along with methodologies used for calculating the projections.