Population: methodology

Resident population by county from the Census Bureau's Population Estimates Program (PEP), the official annual estimates between decennial censuses.

Each value is a 1 July estimate. PEP estimates the population on 1 July of the year shown; we store it against that year. It is not an average over the year and not a count — the only actual counts are the decennial censuses.

Every release restates the ones before it, and the revisions are not small. PEP rebuilds its whole post-census series each year as better administrative data on births, deaths and migration arrives. Between the 2024 and 2025 vintages, all eighteen of our Nevada geographies changed for the same year: Nevada's 2024 population went from 3,267,467 to 3,253,543 — 13,924 fewer people — and Clark County alone fell by 13,125. A figure cited from the earlier vintage is one the Census Bureau no longer publishes.

We never overwrite what came before: each run stores its values under a new vintage, so the number you cited stays retrievable. If you need to reproduce a figure as it stood on a given date, that is what the API's asof mode is for.

The 2020 rebase breaks the series in two. Estimates for 2010–2019 are carried forward from the 2010 census; estimates from 2020 start again from the 2020 census. The two are produced in separate programs and published in separate files, and the step between 2019 and 2020 mixes a real population change with a change of method. Treat growth rates across that boundary with suspicion.

Why these figures differ from our BEA population series. The BEA regional accounts use PEP as their population denominator, but a BEA release incorporates whichever PEP vintage was current when it was built, so it can sit a vintage behind. Where the two disagree for the same year, this series is the more recent statement of the same underlying estimate.

Source. Taken from the Population Estimates county total files rather than the Census API: the API requires a key, and its pep/population dataset stops at the 2021 vintage, so it can no longer supply current estimates.