How does Williamson County's growth rank in Texas? (DRAFT – not published)

In short

• Williamson County is the 12th-largest county in Texas, with about 752,800 people in mid-2025.¹²
• It added about 143,800 people since 2020, the 7th-most of any Texas county (our math).¹²
• In 2024-25, only two counties gained more people moving in from other U.S. places: Collin and Montgomery.¹²

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

How it works

• The U.S. Census Bureau makes a yearly estimate for all 254 Texas counties. Each one is for July 1.¹
• We compare the bureau’s April 2020 base with July 2025. That is a little over five years.¹
• Rankings by percent can mislead for small counties, so we rank percent growth only among the 40 counties that had at least 100,000 people in 2020.²

What the numbers show

Fastest percent growth since 2020, counties with at least 100,000 people in 2020:

Rank	County	2020 base	July 2025	Growth (our math)
1	Kaufman	145,337	209,235	+44.0%
2	Rockwall	107,884	140,738	+30.5%
3	Comal	161,449	209,166	+29.6%
4	Hays	241,064	304,390	+26.3%
5	Montgomery	620,551	781,194	+25.9%
6	Ellis	192,460	240,867	+25.2%
7	Parker	148,241	184,767	+24.6%
8	Williamson	609,059	752,827	+23.6%

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

• Williamson made up about 5.6% of all Texas growth since 2020, while holding about 2.4% of the state’s people (our math).¹²
• Most counties that grew faster are much smaller. Among counties with more than 500,000 people, only Montgomery grew faster.¹²

The other side

• Big growth is not good or bad by itself. This page counts people. It does not weigh the costs or gains of growth.
• Estimates are not counts. The bureau revises them each year. The true number will not be known until the 2030 census.¹
• Other reports use other numbers. The county’s own audit used 727,480 for 2025. See county population growth.

Changes to this page

• 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

• What growth pace do the county’s long-range plans assume?
• How does the county decide when growth calls for more staff?

What we still don’t know

• Whether this pace will hold. The Census file shows the past, not the future.

Footnotes

1. U.S. Census Bureau, Vintage 2025 county population estimates (CO-EST2025-ALLDATA), all 254 Texas counties: April 1, 2020 estimates base, July 1, 2025 estimate, and 2024-25 domestic migration. Williamson 609,059 base; 752,827 in 2025; domestic migration 14,764 (Collin 24,102; Montgomery 22,690). Texas 29,149,498 base; 31,709,821 in 2025. https://www2.census.gov/programs-surveys/popest/datasets/2020-2025/counties/totals/co-est2025-alldata.csv ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷ ↩⁸ ↩⁹

2. Our math. Gain = July 2025 − 2020 base: Williamson 752,827 − 609,059 = 143,768; sum of all 254 county gains 2,560,323; 143,768 ÷ 2,560,323 = 5.6%; 752,827 ÷ 31,709,821 = 2.4%. Ranks are by sorting all 254 counties (size, gain, domestic migration) or the 40 counties with a 2020 base of 100,000 or more (percent growth). ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶