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zipcodes.pro — ZIP/78665

78665

ZIP 78665 is in Round Rock, Texas, in Williamson County; area codes 512 and 737; Central time. Round Rock has 6 ZIP codes; the others are 78664, 78680, 78681, 78682 and 78683.

Type
Standard
Time zone
America/Chicago
County
Williamson
Population
66,171
Coordinates
30.5489, -97.6362
☼ Live from 78665 — Round Rock, TX

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Local time: —

Where 78665 is

Approximate ZIP boundary (Census ZCTA 2020). ZIP codes are mail routes, not areas, so the shape shown is the Census tabulation area that approximates it.

★ Weird and wonderful facts about 78665
  • 🔢 Type 78665 into a pocket calculator and turn it upside down: SggBL — not quite a word, sorry.
  • ➕ As a number, 78,665 = 5 × 15733. Its digits add up to 32, a total 644 other ZIP codes share.
  • 💾In binary, the way a computer stores it: 10011001101001001
  • 🏠 Its numerical neighbours: 78664 (Round Rock, TX, 3 mi away) and 78666 (San Marcos, TX, 51 mi away).
  • 🔄 Backwards, 78665 becomes 56687 — and that is a real ZIP code: Wilton, MN, 1,180 miles away.
  • 👥 19 other ZIP codes are made of exactly the same digits (56678, 56687, 65768, 65786, 66758, 66857, …). The farthest-flung twin is 56687 in Wilton, MN, 1,180 miles away.
  • 🧭 Farther south than 91% of all ZIP codes, and farther west than 76%.
  • 🎯643 miles south of the geographic center of the Lower 48, near Lebanon, Kansas.
  • 🌏 Dig straight through the Earth from 78665 and you would come out at 30.55°S, 82.36°E — 1,445 miles from Port-aux-Français, French Southern Territories, the nearest big city to that spot.
  • ☀Longest day of the year: 14h 07m of daylight. Shortest: 10h 10m.
  • 📏 At 24.1 square miles of land, 78665 is bigger than 41% of ZIP codes — room for about 18 Central Parks.
🌙 The sky over 78665 today
  • Working out the sun…
🌋 Shake report
  • Checking the USGS…

Source: USGS.

People and housing

Population66,171This ZIP66,171
Households24,162This ZIP24,162
Housing units25,598This ZIP25,598
Median age35.5This ZIP35.5Texas35.6US 38.9
Median household income$122,680This ZIP$122,680Texas$78,476US $80,734
Median home value$474,100This ZIP$474,100Texas$283,800US $332,700
Median gross rent$1,938This ZIP$1,938Texas$1,403US $1,413
Bachelor's degree or higher53.6%This ZIP53.6%
Mean commute27.8 minThis ZIP27.8 min
Population density2,748.3 / sq miThis ZIP2,748.3 / sq mi

Business and tax activity

Business establishments981This ZIP981
Employees16,807This ZIP16,807
Annual payroll$949,925,000This ZIP$949,925,000
Tax returns filed30,230This ZIP30,230
Total adjusted gross income$3,242,465,000This ZIP$3,242,465,000

Land area

Land area24.08 sq miThis ZIP24.08 sq mi
Water area0.36 sq miThis ZIP0.36 sq mi

Other place names in 78665

Census places whose land this ZIP code overlaps. The Postal Service may accept other city names in an address, too.

ZIP codes near 78665

ZIPCityDistance
78664 Round Rock, TX 3.1 mi
78681 Round Rock, TX 4.8 mi
78634 Hutto, TX 5.5 mi
78627 Georgetown, TX 6.3 mi
78728 Austin, TX 7.2 mi
78764 Austin, TX 7.3 mi
78626 Georgetown, TX 7.6 mi
78691 Pflugerville, TX 7.6 mi
78680 Round Rock, TX 7.7 mi
78682 Round Rock, TX 7.7 mi

Find every ZIP code within 10 miles of 78665 →

Questions about this ZIP code

Where is ZIP code 78665?

78665 is in Round Rock, Texas, in Williamson County, part of the Austin-Round Rock-San Marcos, TX metropolitan area. Its published point location is 30.5489, -97.6362.

What county is 78665 in?

78665 lies in Williamson County.

What area code is 78665?

Round Rock uses area codes 512 and 737, from NANPA's telephone records.

What time zone is 78665 in?

78665 uses America/Chicago.

How many people live in 78665?

About 66,171 people live in ZIP code 78665, in 24,162 households, at 2,748.3 people per square mile. These are American Community Survey 5-year estimates for the ZIP Code Tabulation Area, not a headcount.

What is the median household income in 78665?

$122,680 a year, against $78,476 across Texas.

What ZIP codes are near 78665?

The closest are 78664 (3.1 mi), 78681 (4.8 mi), 78634 (5.5 mi), 78627 (6.3 mi) and 78728 (7.2 mi).

Is 78665 a PO Box ZIP code?

78665 is a standard ZIP code. A normal ZIP code with street delivery.

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Cite this page

zipcodes.pro. “78665 ZIP Code — Round Rock, Texas (Williamson County).” Data release 2026-10-12. Retrieved 2026-10-20. https://zipcodes.pro/zip/78665

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