🇺🇸 United States ZIP Code

STANDARD

78665

Round Rock

ZIP Code 78665 is a standard zip code serving Round Rock, Round Rock, Texas (TX), in Williamson County, United States. It has an estimated population of 35,985 with a median household income of $85,907. The area falls within the America/Chicago timezone.

Median Household Income vs. National Average

Location

Country: 🇺🇸 United States
State / Province: Texas (TX)
County: Williamson
City: Round Rock
Timezone: America/Chicago

Coordinates

Latitude: 30.514500
Longitude: -97.668000

Geographic Details

Land Area: 18.75 mi²
Water Area: 0.30 mi²
Population Density: 1919.0 people per mi² (80th percentile)
Bounding Box: 30.587262°N, 30.496310°S, -97.601171°E, -97.692855°W

With 35,985 residents spread across 18.75 square miles, this area has a population density of 1919.0 people per square mile.

Demographics

35,985

Population

90th percentile

$85,907

Median Income

90th percentile

$186,900

Median Home Value

70th percentile

18.75 mi²

Land Area

The median household income in 78665 is $85,907, and the median home value is $186,900. This places the area in the top 25% nationally for household income.

Housing

12,870

Total Units

12,056

Occupied Units

93.7%

Occupancy Rate

Nearby ZIP Codes

Other zip codes in Round Rock, TX.

78664

Round Rock

78680

Round Rock

78681

Round Rock

78682

Round Rock

78683

Round Rock

Similar ZIP Codes in Texas

ZIP codes with similar median household income in Texas.

76066

Millsap

$80,088

75023

Plano

$74,777

76054

Hurst

$93,763

77354

Magnolia

$75,269

75166

Lavon

$75,804

76001

Arlington

$74,587

78652

Manchaca

$76,604

78121

La Vernia

$83,892

Frequently Asked Questions

What information is available for each ZIP code?

Each ZIP code page shows city, state, county, geographic coordinates, timezone, population, median household income, median home value, housing units, land area, population density, commute time, educational attainment, area codes, and ZIP code type (Standard, PO Box, or Unique).

What are the different types of ZIP codes?

There are three types of ZIP codes: Standard (residential and commercial delivery areas), PO Box (assigned to post office box sections), and Unique (assigned to a single high-volume address like a government agency or large company). Standard ZIP codes are the most common.

How often is ZIP code data updated?

ZIP code assignments are updated quarterly by the USPS. Demographic data comes from the US Census Bureau's American Community Survey (ACS), which releases new 5-year estimates annually. ZipFYI updates its data to reflect the latest available information.

What is population density and why does it matter?

Population density measures the number of people per square mile in a ZIP code area. It helps identify urban vs. rural areas, affects real estate values, impacts service availability, and is used in market analysis. Dense urban ZIP codes may have 50,000+ people per square mile.

How are ZIP code boundaries determined?

ZIP code boundaries are determined by the USPS based on mail delivery routes, not political or geographic boundaries. They follow carrier routes and may cross city, county, or even state lines. Boundaries can change when the USPS reorganizes delivery operations.

What does median household income tell me about a ZIP code?

Median household income is the middle value when all household incomes in a ZIP code are sorted. Half of households earn more and half earn less. It is a better indicator of typical earnings than average income, which can be skewed by very high or very low outliers.