Residential delivery area · Texas
ZIP Code 78665: Round Rock, TX
ZIP code 78665 is in Round Rock, Texas, entirely in Williamson County (Census 2020 ZIP-county file). About 66,000 people live there (Census Bureau, ACS 2020-2024), the most populous of Round Rock's 3 residential ZIP codes. Median household income is $122,680 (Census Bureau, ACS 2020-2024). By Census place, 61% of its land lies in Round Rock; 40% is outside any Census place.
- ACS2020-24
- Census2020
- FHFA2025
- ZBP2023
- IRS2022
- Town
- Round Rock · 3 residential ZIPs
- County
- Williamson County
- Census places
- Round Rock
- Metro area
- Austin-Round Rock-San Marcos, TX
- House districts
- TX-31 (81%), TX-17 (19%) 119th Congress, by share of land
- State
- Texas
- Time zone
- Central
- Land area
- 24.1 sq mi · 2,748 people per sq mi
Where is ZIP code 78665?
78665 centers on 30.549°, -97.636° and covers 24.1 square miles of land plus 0.4 of water. It borders 4 ZIP codes: 78664, 78681, 78634, 78626.
The map draws ZIP code areas only. For the streets inside 78665, open its center on OpenStreetMap.
Source: U.S. Census Bureau, 2020 ZCTA cartographic boundaries and the 2023 Gazetteer (2020 ZCTAs); ZIP-to-county shares, Census places and House districts (119th Congress) from the Census 2020 relationship files (shares of land); metro area from the OMB delineation (July 2023); town name and time zone from simplemaps US ZIP Codes (CC BY 4.0).
How does 78665 compare with the rest of Round Rock?
| Measure | 78665 | In Round Rock | In Williamson County | In TX |
|---|---|---|---|---|
| People (ACS 2020-2024) | 66,171 | 1st of 3 | 3rd of 27 | 60th of 1,990 |
| Median household income | $123k | 2nd of 3 | 7th of 22 | 100th of 1,172 |
| Median home value | $474k | 2nd of 3 | 11th of 24 | 126th of 1,172 |
Its median household income is higher than in 91% of U.S. residential ZIP codes, and it is denser than 88% of all U.S. residential ZIP codes. ZIP codes at the ACS caps ($250,000 or more for household income, $2,000,000 or more for home value) share the top rank.
Source: U.S. Census Bureau, ACS 2020-2024 5-year estimates (B01003, B19013, B25077); ranks by PlainZIP over residential ZIP codes (ZCTAs).
How many people live in 78665?
The 2020 Census counted 61,577 people in 78665; the ACS, which samples households over 2020-2024, estimates 66,171. Its boundary changed between the 2010 and 2020 censuses, so the two counts are not compared.
- People, ACS 2020-2024
- 66,171
- 2020 Census count
- 61,577
- Households
- 24,162
- Median age
- 35.5
Source: U.S. Census Bureau, ACS 2020-2024 5-year estimates (B01003, B01002, B11001); 2020 Census (DHC P1); 2010 Census (SF1 P1).
Who lives in 78665?
Of the 66,171 people the ACS estimates in 78665, 25.5% are under 18 and 10.4% are 65 or older. The largest group by race and Hispanic origin is White (not Hispanic) (45.4%), then Hispanic or Latino (24.3%).
- Under 1825.5%
- 18 to 6464.1%
- 65 and older10.4%
- White, not Hispanic45.4%
- Hispanic or Latino24.3%
- Black, not Hispanic11.5%
- Asian, not Hispanic11.5%
- Other or two or more7.4%
Source: U.S. Census Bureau, ACS 2020-2024 5-year estimates (B01001 age by sex, B03002 Hispanic or Latino origin by race); shares of the estimated population, small ZIP codes carry wide margins.
What do households in 78665 earn?
Median household income is $122,680 (ACS 2020-2024), the 7th highest of the 22 ranked ZIP codes in Williamson County.
- Median household income
- $122,680
- Income per person
- $56,191
- Below the poverty line
- 4.7%
- Unemployed (of the labor force)
- 3.4%
- Adults 25+ with a bachelor's degree
- 53.6%
- Adjusted gross income per tax return, 2022
- $107,26030,230 returns; wages 81% of AGI (IRS)
Source: U.S. Census Bureau, ACS 2020-2024 and 2015-2019 5-year estimates (B19013, B19301, B17001, B23025, B15003; 2015-2019 dollars converted with the BLS CPI-U, 1.22699); IRS Statistics of Income, ZIP code data, tax year 2022 (adjusted gross income per return, filed under the address on the return).
What are homes worth in 78665?
FHFA's house price index for 78665, built from repeat sales and appraisals of the same homes, rose 93% from 2015 to 2025 and rose 47% from 2020 to 2025, and moved +3.5% in 2025.
- Median home value (owners' estimate)
- $474,100
- Median gross rent
- $1,938
- Homes owned by their occupants
- 61.4%
- Housing units
- 25,598
Source: U.S. Census Bureau, ACS 2020-2024 5-year estimates (B25077, B25064, B25003, B25001); FHFA House Price Index, annual five-digit ZIP, updated 2026-03-31.
What businesses are in 78665?
981 business establishments had a location in this ZIP code in 2023, 335 more than in 2018; the most are in professional, scientific, and technical services (ZIP Code Business Patterns).
- Professional, scientific, and technical services163
- Health care and social assistance145
- Construction101
- Other services (except public administration)94
- Accommodation and food services90
- Retail trade83
Source: U.S. Census Bureau, ZIP Code Business Patterns 2023 and 2018 (establishments with paid employees, by the business's ZIP code).
Which ZIP codes are next to 78665?
| ZIP | Town | People | Household income | Distance |
|---|---|---|---|---|
| 78664 | Round Rock | 62,060 | $87k | 3.1 mi |
| 78681 | Round Rock | 56,691 | $138k | 4.8 mi |
| 78634 | Hutto | 46,413 | $114k | 5.5 mi |
| 78626 | Georgetown | 48,072 | $100k | 7.6 mi |
| 78728 | Austin | 26,777 | $75k | 7.2 mi (near) |
| 78660 | Pflugerville | 124,834 | $113k | 7.9 mi (near) |
| 78717 | Austin | 37,262 | $145k | 8.1 mi (near) |
| 78674 | Weir | 108 | – | 8.7 mi (near) |
Source: PlainZIP from the Census 2020 ZCTA boundaries (shared edges) and internal points; figures ACS 2020-2024.