What is the largest city in Williamson County, TX?

Round Rock is the largest city or town in Williamson County, with about 127,786 residents.

How many ZIP codes are in Williamson County?

Williamson County includes 19 ZIP Code Tabulation Areas, including 76527, 76530, 76537, 76573, 76574.

What is the population of Williamson County, TX?

About 672,688 people live in Williamson County, based on American Community Survey 5-year estimates.

What counties border Williamson County?

Williamson County borders Travis County, Bell County, Bastrop County, Burnet County, Milam County, Lee County.

Williamson County, TX: Cities, ZIP Codes & Local Data

Population

672,688

Land area

1,116sq mi

People per sq mi

603

ZIP codes

19

Williamson County at a glance

Williamson County is about 5.2 times as dense as Texas as a whole.
By population, it ranks 12th among 254 counties in Texas.
The median household income is $111,340, 42% above the Texas median of $78,476.
A typical owner-occupied home is valued at $447,000 (58% above Texas) and median rent is $1,796 a month.
Its largest cities are Round Rock (127,786), Georgetown (85,999) and Cedar Park (78,301).

Local data for Williamson County, TX

Counts from official public data

Housing and community stats

Williamson County, TX, American Community Survey 2020-2024

Full profile

Median household income

$111,340

Poverty rate

6.4%

Median home value

$447,000

Prices -1.0% in a year

Median rent

$1,796/mo

Homeownership

66.4%

Bachelor's or higher

48.4%

Median age

37.3

Average commute

27.9 min

Largest reported origins and ancestries: Mexican Americans (124,519), German Americans (94,066), Irish Americans (55,791).

Home values and rents Income, education and commute

Economy and federal money

Jobs, income, federal spending and pandemic loans

Details

Unemployment rate

3.7%

Sep 2026, -0.1 pts in a year

Average annual pay

$82,562

238,420 jobs, 2025

Income per person

$76,156

BEA, 2024

Federal spending

$4.8B

FY 2026, $7,808 per person

PPP loans

$874M

14,054 loans, 111,432 jobs reported

Campaign donations

$4.9M

Itemized, 2026 cycle

Economy Federal spending PPP loans

How people get to work

Williamson County, TX, workers 16 and older. American Community Survey 5-year estimates

Drove alone63.9%
Carpooled7.7%
Public transit0.3%
Walked0.8%
Bicycle0.2%
Taxi, ride-hailing, motorcycle or other1.7%
Worked from home25.4%

Average one-way commute: 27.9 minutes for people who do not work from home.

Environment and hazard risk

Williamson County, TX, from FEMA, NOAA and EPA

Full report

Natural hazard risk

Relatively Moderate

Top: hail

Storm events since 1996

876

Most often hail

Flood insurance policies

1,949

1.1% of homes, county

July high / Jan low

96° / 36°F

37.1 inches of rain a year

Hazards, floods and storm history Check a flood zone 66 historic places

Health statistics

Share of adults in Williamson County, TX, CDC PLACES estimates

All 40 measures

Obesity

32.6%

U.S. 33.3% -0.7 pts

Diabetes

9.8%

U.S. 12.1% -2.3 pts

Smoking

9.9%

U.S. 12.8% -2.9 pts

Uninsured (18-64)

12.2%

U.S. 11.1% +1.1 pts

Cities, towns and ZIP codes in Williamson County

Population shown

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Frequently asked questions

What is the largest city in Williamson County, TX?: Round Rock is the largest city or town in Williamson County, with about 127,786 residents.
How many ZIP codes are in Williamson County?: Williamson County includes 19 ZIP Code Tabulation Areas, including 76527, 76530, 76537, 76573, 76574.
What is the population of Williamson County, TX?: About 672,688 people live in Williamson County, based on American Community Survey 5-year estimates.
What counties border Williamson County?: Williamson County borders Travis County, Bell County, Bastrop County, Burnet County, Milam County, Lee County.