Williamson County, Texas demographics
Williamson County, Texas (county FIPS 48491) has a median household income of $111,340 (±$1,581) and a total population of 672,688 in the American Community Survey 5-year estimates for 2020-2024.
Margins of error are at the 90% confidence level. The figures describe 2020-2024 (dollars in 2024 dollars), not the present. 27 ZIP Code Tabulation Areas overlap the county (Census 2020).
Data as of Oct 22, 2026 (Olympus publication) · Markdown version
- Values are ACS 5-year estimates for 2020-2024 (dollars in 2024 dollars), not current figures.
- ZCTA-county overlaps come from the Census 2020 relationship file and use 2020 counties, by land area; Connecticut uses its legacy counties, not the planning regions in ACS 2022+.
ACS 5-year estimates, 2020-2024
Census American Community Survey 5-year estimates for 2020-2024, with 90% margins of error as published by the Census Bureau.
| Metric | Estimate | Margin of error (90%) | ACS table |
|---|---|---|---|
| Total population | 672,688 | none (controlled estimate) | B01003 |
| Median age | 37.3 years | ±0.2 years | B01002 |
| Households | 252,323 | ±1,054 | B11001 |
| Median household income (inflation-adjusted to the final ACS year) | $111,340 | ±$1,581 | B19013 |
| Median value of owner-occupied housing units | $447,000 | ±$3,593 | B25077 |
| Median gross rent | $1,796 | ±$17 | B25064 |
| Owner-occupied share of occupied housing units | 66.4% | none (derived from several estimates) | B25003 (derived) |
| Renter-occupied share of occupied housing units | 33.6% | none (derived from several estimates) | B25003 (derived) |
| High school graduate or higher (age 25+) | 94.1% | none (derived from several estimates) | B15003 (derived) |
| Bachelor's degree or higher (age 25+) | 48.4% | none (derived from several estimates) | B15003 (derived) |
| Share of people below the poverty level | 6.4% | none (derived from several estimates) | B17001 (derived) |
| Unemployment rate (civilian labor force) | 3.9% | none (derived from several estimates) | B23025 (derived) |
- Dollar values are in 2024 inflation-adjusted dollars.
- Percentages' margins of error are in percentage points (pp).
Geography
| Measure | Value |
|---|---|
| County FIPS | 48491 |
| Land area | 1,115.85 sq mi |
| Water area | 16.04 sq mi |
| Population density | 603 per sq mi of land |
| Geography vintage | 2024 Gazetteer |
ZIP codes (ZCTAs) in this county
ZCTAs that overlap the county in the Census 2020 ZCTA to county relationship file, largest share of the county's land first.
| ZCTA | Share of county land | Share of ZCTA land | County is the ZCTA's primary county |
|---|---|---|---|
| 76574 | 13.3% | 99.9% | Yes |
| 76527 | 9.2% | 85.7% | Yes |
| 78642 | 9.2% | 92% | Yes |
| 76530 | 8.3% | 100% | Yes |
| 78626 | 7.9% | 100% | Yes |
| 78633 | 7% | 100% | Yes |
| 76578 | 5.8% | 99.2% | Yes |
| 78628 | 5.8% | 100% | Yes |
| 78634 | 5% | 99.6% | Yes |
| 76537 | 4.8% | 100% | Yes |
| 78641 | 4.1% | 37.1% | |
| 78615 | 3.1% | 63.9% | Yes |
| 76511 | 2.7% | 36.7% | |
| 78621 | 2.3% | 14.3% | |
| 78613 | 2.2% | 88.6% | Yes |
| 78665 | 2.2% | 100% | Yes |
| 78681 | 2.1% | 100% | Yes |
| 78664 | 1.3% | 85.6% | Yes |
| 76577 | 1.2% | 9.6% | |
| 78717 | 1.2% | 100% | Yes |
| 78729 | 0.8% | 88.4% | Yes |
| 78750 | 0.2% | 21.9% | |
| 78728 | 0.2% | 21.7% | |
| 76573 | 0.1% | 100% | Yes |
| 78674 | 0% | 100% | Yes |
| 78759 | 0% | 1.1% | |
| 78727 | 0% | 1.9% |
Sources
- American Community Survey 5-year estimates (Census Data API) — U.S. Census Bureau. ACS 5-year 2020-2024 (release acs5-2024:county), source date 2025-09-02. https://api.census.gov/data/2024/acs/acs5?get=NAME,B01003_001E,B01003_001M,B01002_001E,B01002_001M,B11001_001E,B11001_001M,B19013_001E,B19013_001M,B25077_001E,B25077_001M,B25064_001E,B25064_001M,B25003_001E,B25003_002E,B25003_003E,B15003_001E,B15003_017E,B15003_018E,B15003_019E,B15003_020E,B15003_021E,B15003_022E,B15003_023E,B15003_024E,B15003_025E,B17001_001E,B17001_002E,B23025_003E,B23025_005E&for=county:491&in=state:48
- Published by Olympus on Oct 22, 2026.
- Source data: U.S. Census Bureau. Works of the U.S. government are not subject to copyright in the United States.
- This product uses the Census Bureau Data API but is not endorsed or certified by the Census Bureau.
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curl -s "https://api.olympus.new-odyssey.com/v1/geo-demographics/counties/48491" -H "X-API-Key: $OLYMPUS_API_KEY"get_us_demographics {"county_fips":"48491"}