In short

  • The county added about 23,800 people in the year to July 2025, down from about 29,200 in the year to July 2021.1
  • Most growth still comes from people moving in from other U.S. places, but that number fell from about 26,700 to about 14,800 a year.1
  • Births rose from about 7,100 to about 8,500 a year. Births now outnumber deaths by more than 2 to 1.12

Numbers marked “our math” are our estimates, not official figures. The notes show the inputs and the steps.

How it works

  • Each year the Census Bureau estimates how a county changed from one July 1 to the next.1
  • It splits the change into parts: births minus deaths, people moving from other countries, and people moving from other U.S. places.1
  • These are estimates. A small leftover amount does not fit any part.1

What the numbers show

Year ending July 1Total changeBirthsDeathsMoved from other countriesMoved from other U.S. places
2021+29,1797,1373,86975426,658
2022+29,6888,0654,0494,19420,188
2023+27,3208,1793,9265,25017,467
2024+27,2158,4643,9247,75114,763
2025+23,8148,5033,9514,61814,764

Source: U.S. Census Bureau, 2025 county population estimates.1

  • Moves from other U.S. places fell about 45% from 2021 to 2025 (our math).12
  • Births minus deaths added about 4,600 people in 2025, up from about 3,300 in 2021.1
  • The county had about 752,800 people in July 2025. See county population growth.1

The other side

  • Slower is still fast. The county still grew about 3% in the last year, far faster than Texas as a whole (about 1.2%, our math).12
  • One year can be unusual. These estimates do not say why moves went up or down in any year, so a single starting year can make a change look larger or smaller.
  • Estimates get revised. Each new release can change these numbers.1

Changes to this page

  • Nov. 2, 2026: We changed wording so it says no more than our sources show.
  • Nov. 2, 2026: Rewrote the questions to ask so each is open, neutral and addressed to the public body.
  • Nov. 2, 2026: We checked every figure against its source. We reworded the other-side points so they stick to what the sources show.

Questions to ask

  • How do county plans for roads, courts and jail space account for changes in the pace of moves?
  • Which parts of the county are getting most new residents, by the county’s data?

What we still don’t know

  • Why fewer people moved in. The estimates show how many, not why.
  • Where in the county new residents settled. This page uses county totals only.

Footnotes

  1. U.S. Census Bureau, Vintage 2025 county population estimates (CO-EST2025-ALLDATA), Williamson County and Texas: yearly population change, births, deaths, international migration and domestic migration, 2021–2025. https://www2.census.gov/programs-surveys/popest/datasets/2020-2025/counties/totals/ ↩ ↩2 ↩3 ↩4 ↩5 ↩6 ↩7 ↩8 ↩9 ↩10 ↩11 ↩12

  2. Our math. Domestic moves (14,764 − 26,658) ÷ 26,658 = −44.6%. Births to deaths 2025: 8,503 ÷ 3,951 = 2.2. Growth 2025: 23,814 ÷ 729,013 = 3.3%; Texas 391,243 ÷ 31,318,578 = 1.2%. ↩ ↩2 ↩3