ZIP codes in Williamson County, Texas
Williamson County has 27 ZIP codes. 13 lie entirely inside it and 14 are shared with neighboring counties, so part of their land and their people are elsewhere. About 670,911 people live in the parts inside it (ACS 2020–2024).
By the All Map Tools Team
- ZIP codes
- 27
- With 1% or more of their land inside
- Entirely inside
- 13
- 99% or more of their land
- Shared with other counties
- 14
- Most with Travis County (10)
- Most populated ZIP
- 78613
- 89,956 people · Cedar Park
- Least populated ZIP
- 78674
- 108 people · Weir; 1 more with nobody living there
- Largest ZIP by land
- 76574
- 149 sq mi · Taylor
Map of the ZIP codes in Williamson County
- Entirely in the county (99% or more of its land)
- Shared, mostly in this county
- Shared, mostly in other counties
- Neighboring counties
Each area is a ZIP code with its number where it fits. Hover over one to see its name.
All ZIP codes in Williamson County
| ZIP code | Main city | Population | Land in the county | Residents in the county |
|---|---|---|---|---|
| 76511 | Bartlett | 2,702 | 37% | ≈ 1,367 |
| 76527 | Florence | 4,918 | 86% | ≈ 4,308 |
| 76530 | Granger | 2,598 | 100% | 2,598 |
| 76537 | Jarrell | 16,272 | 100% | 16,272 |
| 76573 | — | 0 | 100% | 0 |
| 76574 | Taylor | 20,242 | 99.8% | ≈ 20,142 |
| 76577 | Thorndale | 3,128 | 9.6% | ≈ 332 |
| 76578 | Thrall | 1,762 | 99.2% | ≈ 1,748 |
| 78613 | Cedar Park | 89,956 | 89% | ≈ 80,919 |
| 78615 | Coupland | 1,637 | 64% | ≈ 245 |
| 78621 | Elgin | 30,411 | 14% | ≈ 699 |
| 78626 | Georgetown | 48,072 | 100% | 48,072 |
| 78628 | Georgetown | 50,822 | 100% | 50,822 |
| 78633 | Georgetown | 29,309 | 100% | 29,309 |
| 78634 | Hutto | 46,413 | 99.5% | ≈ 45,719 |
| 78641 | Leander | 99,865 | 37% | ≈ 80,880 |
| 78642 | Liberty Hill | 26,434 | 92% | ≈ 25,739 |
| 78664 | Round Rock | 62,060 | 86% | ≈ 55,858 |
| 78665 | Round Rock | 66,171 | 100% | 66,171 |
| 78674 | Weir | 108 | 100% | 108 |
| 78681 | Round Rock | 56,691 | 100% | 56,691 |
| 78717 | Austin | 37,262 | 100% | 37,262 |
| 78727 | Austin | 29,958 | 1.9% | ≈ 893 |
| 78728 | Austin | 26,777 | 22% | ≈ 3,256 |
| 78729 | Austin | 30,460 | 88% | ≈ 25,549 |
| 78750 | Austin | 29,277 | 22% | ≈ 14,988 |
| 78759 | Austin | 43,182 | 1.1% | ≈ 964 |
ZIP codes shared with other counties
These 14 ZIP codes have part of their land in another county. The first figure is the share of their land in Williamson County; then, where the rest lies.
- 76511 (Bartlett): 37% here; 57% in Bell County and 6.2% in Milam County.
- 76527 (Florence): 86% here; 7.6% in Burnet County and 6.6% in Bell County.
- 76577 (Thorndale): 9.6% here; 90% in Milam County.
- 78613 (Cedar Park): 89% here; 11% in Travis County.
- 78615 (Coupland): 64% here; 36% in Travis County.
- 78621 (Elgin): 14% here; 63% in Bastrop County, 15% in Travis County, and 8.6% in Lee County.
- 78641 (Leander): 37% here; 63% in Travis County.
- 78642 (Liberty Hill): 92% here; 8.0% in Burnet County.
- 78664 (Round Rock): 86% here; 14% in Travis County.
- 78727 (Austin): 1.9% here; 98% in Travis County.
- 78728 (Austin): 22% here; 78% in Travis County.
- 78729 (Austin): 88% here; 12% in Travis County.
- 78750 (Austin): 22% here; 78% in Travis County.
- 78759 (Austin): 1.1% here; 99% in Travis County.
Cities and prefixes
By main city (the city, town or CDP each ZIP shares the most land with), the ones with the most are Austin (6), Georgetown (3), Round Rock (3), Bartlett (1), Cedar Park (1), and Coupland (1); 17 places in all.
They start with 3 different three-digit prefixes, one per USPS sorting center: 765, 786, and 787.
Neighboring counties
Each one with its ZIP codes. Those without a page of their own open in the tool.
Tools for this county
Sources
- U.S. Census Bureau, 2020 ZCTA to County, ZCTA to Place and ZCTA to Census Tract Relationship Files (and the 2022 County Subdivision to ZCTA file for Connecticut). Public domain.
- U.S. Census Bureau, American Community Survey 2020–2024 5-year estimates, table B01003 (population of each ZIP code, census tract and Connecticut town). Public domain.
- U.S. Census Bureau, Vintage 2025 Population Estimates (county population) and 2025 Gazetteer Files (land area and interior point of each ZIP code). Public domain.
- U.S. Census Bureau, Cartographic Boundary Files: ZCTAs 2020 and counties 2025, 1:500,000; county adjacency file 2025. Public domain.
How we count. ZIP codes here are the Census Bureau’s ZIP Code Tabulation Areas (ZCTAs), the areas it draws to match USPS ZIP codes; ZIPs with no area of their own (PO boxes, single buildings) aren’t included. A ZIP can cross county lines: “Land in the county” is the exact share of its land inside, from the Census relationship files. “Residents in the county” is the whole ZIP for those entirely inside; for shared ones it’s an estimate, spreading the people of each census tract over the land it shares with the ZIP. Population: ACS 2020–2024. Methodology.
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