SOURCES, VERSIONS & WHAT CHANGED

County population: source and preparation record

The first ACD county population edition prepares one consistent Census vintage for comparing population growth and its demographic components.

3,144counties and equivalents

18,864county / year records

2020–2025July population estimates

2025Census source vintage

Source edition and measurement periods

Census released Vintage 2025 county estimates March 26, 2026. The series covers July 1 populations from 2020 through 2025 on January 1, 2025 county boundaries. ACD captured and prepared it October 18, 2026 UTC. These dates describe source coverage, publication and preparation separately.

The 2020 components cover only April 1–June 30, beginning at the revised census base. Each later record covers July 1 of the preceding year through June 30. We preserve that initial-quarter distinction and the unpublished 2020 rate cells.

What preparation adds

The county summary supplies all six July population levels, recent and five-year growth, and the latest components. The long history has explicit population and component dates, counts, original per-1,000 rates and derived growth percentages. Five-digit FIPS codes, accented names, genuine negatives and zeros survive the transformation. The source CSV is transcoded from ISO-8859-1 to UTF-8 without changing its cells.

Coverage and checks

All 3,144 counties and equivalents in the 50 states and DC have six history rows. This includes Connecticut’s nine planning regions. Puerto Rico and other territories are outside the file. All 3,195 original records are accounted for; 51 state/DC records are excluded from the county product but used to check every one of the 62 count fields against county sums.

All population balances and published rate formulas pass. Independent acceptance compares every delivered source-derived cell, calculated growth value, period and audit outcome with the original CSV. Retained inputs, lossless staging and recipes reproduce the publication offline.

Interpreting growth and migration

Natural change, net domestic migration, net international migration and the residual sum to population change. Net migration is arrivals minus departures, not gross moves or a count of foreign-born residents. Source component rates use average beginning/end population per 1,000; ACD growth percentages use beginning population. The five-year summary compares July 2020 with July 2025.

Time history, source editions and processing revisions

This is one source vintage containing six years of estimates. A later Census vintage can revise earlier years as well as add another year. The growth fields here describe change within Vintage 2025; they are not differences between source editions or ACD processing versions. This is the first ACD release, so no release-to-release comparison is claimed.

Processing improvements using these retained inputs are included for buyers. A future source vintage may be sold separately after purchaser-entitlement review. No subscription, scheduled refresh, forecast or unpublished confidence interval is included.