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City ZIP codes · Texas

Round Rock, TX ZIP Codes

6 ZIP codes use the postal name Round Rock, Texas (Census 2020 ZCTAs and GeoNames postal codes, October 2026): 3 residential and 3 for PO boxes or a single organization. Median household income runs from $87,417 in 78664 to $137,819 in 78681, 1.6 times as much (Census Bureau, ACS 2020-2024). Round Rock's most populous ZIP code is 78665, with 66,171 people (ACS 2020-2024); 61% of its land is in the city of Round Rock.

  • ACS2020-24
  • Census2020
  • GeoNames2026

Where are Round Rock's ZIP codes?

78664: $87k median household income78665: $123k median household income78681: $138k median household income78681786647866578664: $87k median household income78665: $123k median household income78681: $138k median household income78681786647866578664: $87k median household income78665: $123k median household income78681: $138k median household income786817866478665
The 3 residential ZIP codes named Round Rock, shaded by median household income in national fifths (ACS 2020-2024). Select a ZIP to open it. <$54.1k$98.1k+no figure

Source: U.S. Census Bureau, 2020 ZCTA cartographic boundaries; ACS 2020-2024 5-year estimates (B19013).

How different are Round Rock's ZIP codes?

The highest median household income is in 78681 ($137,819), the lowest in 78664 ($87,417). Home values run from $358,200 in 78664 to $497,300 in 78681.

Source: U.S. Census Bureau, ACS 2020-2024 5-year estimates (B19013, B25077, B01003).

All 3 residential ZIP codes of Round Rock

Residential ZIP codes with the postal name Round Rock, TX, largest first (ACS 2020-2024); sort by any column
County
78665 Williamson County 66,171 2,748 $123k $474k
78664 Williamson County 62,060 3,736 $87k $358k
78681 Williamson County 56,691 2,445 $138k $497k

Download the 6 ZIP codes as CSV

Source: U.S. Census Bureau, ACS 2020-2024 5-year estimates; 2023 Gazetteer land areas (2020 ZCTAs); town names from simplemaps US ZIP Codes (CC BY 4.0) and GeoNames (CC BY 4.0).

PO Box and single-organization ZIP codes in Round Rock

3 ZIP codes named Round Rock have no residential delivery area: post office boxes, or one organization (a large employer, an agency, a university) with its own code. The Census Bureau publishes no figures for them.

Round Rock, TX: ZIP codes without a residential area, for PO boxes or one organization (GeoNames postal codes; USPS does not publish openly which is which)
ZIPCounty
78680Williamson County
78682Williamson County
78683Williamson County

Source: GeoNames postal codes (CC BY 4.0); a ZIP code with no Census ZCTA has no residential delivery area.

Which counties do Round Rock's ZIP codes reach?

Round Rock's residential ZIP codes lie in 2 counties: Williamson County (3 ZIP codes mainly there), Travis County (part of a ZIP code).

Which places do Round Rock's ZIP codes cover?

A postal name is not a city limit. By the Census Bureau's places, Round Rock's residential ZIP codes cover Round Rock itself and 2 other places, each listed with the ZIP codes that have at least 5% of their land in it or hold most of the place:

  • Brushy Creek census-designated 78681
  • Pflugerville 78664

Source: U.S. Census Bureau, 2020 ZCTA-to-place relationship file (shares of land).

Which first three digits do Round Rock's ZIP codes use?

The first three digits of a ZIP code name the sectional center, the mail processing plant that sorts it. Every ZIP code of Round Rock starts with 786.

Three-digit prefixes of Round Rock's ZIP codes, the sectional center for each (USPS labeling list L005, effective October 1, 2026) and how many of the prefix's codes are Round Rock's
PrefixSectional centerHereAll codes
786 Austin, TX (SCF 786) 6 75

Source: U.S. Postal Service, labeling list L005 (3-digit ZIP Code prefix groups, SCF sortation), effective October 1, 2026.