Every ZIP code in the United States, with weather, radar, trivia and the numbers behind it. Five digits since 1963!

ZIP stands for Zone Improvement Plan. The codes went live on July 1, 1963.The lowest ZIP code is 00501 — the IRS in Holtsville, New York.The highest ZIP code is 99950, in Ketchikan, Alaska.Type 07734 into a calculator and turn it upside down: hELLO. It is Keansburg, New Jersey.12345 belongs to one company: General Electric in Schenectady, New York.The first digit is a region: 0 is New England and New Jersey, 9 is the West Coast, Alaska and Hawaii.Mr. ZIP, the cartoon mailman, was the mascot that sold the idea to America.ZIP+4 arrived in 1983 and can narrow a ZIP down to one side of one block.A ZIP code is a mail route, not a place: plenty of them cross county and even state lines.Play ZIP Hunt: guess the secret ZIP code of the day in six tries.
zipcodes.pro — ZIP/78681

78681

ZIP 78681 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, 78665, 78680, 78682 and 78683.

Type
Standard
Time zone
America/Chicago
County
Williamson
Population
56,691
Coordinates
30.5418, -97.7166
☼ Live from 78681 — Round Rock, TX

Weather right now

Asking the National Weather Service…

NEXRAD radar
Finding the nearest radar…
Local time: —

Where 78681 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 78681
  • 🔢 Type 78681 into a pocket calculator and turn it upside down: IBgBL — not quite a word, sorry.
  • ➕ As a number, 78,681 = 3 × 26227. Its digits add up to 30, a total 1,024 other ZIP codes share.
  • 💾In binary, the way a computer stores it: 10011001101011001
  • 🏠 Its numerical neighbours: 78680 (Round Rock, TX, 10 mi away) and 78682 (Round Rock, TX, 10 mi away).
  • 🔄 Backwards, 78681 becomes 18687, which is not a ZIP code at all.
  • 👥 11 other ZIP codes are made of exactly the same digits (16878, 17868, 17886, 61878, 68178, 68718, …). The farthest-flung twin is 17868 in Riverside, PA, 1,379 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 78681 and you would come out at 30.54°S, 82.28°E — 1,444 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 23.2 square miles of land, 78681 is bigger than 40% of ZIP codes — room for about 18 Central Parks.
🌙 The sky over 78681 today
  • Working out the sun…
🌋 Shake report
  • Checking the USGS…

Source: USGS.

People and housing

Population56,691This ZIP56,691
Households20,135This ZIP20,135
Housing units20,781This ZIP20,781
Median age39.3This ZIP39.3Texas35.6US 38.9
Median household income$137,819This ZIP$137,819Texas$78,476US $80,734
Median home value$497,300This ZIP$497,300Texas$283,800US $332,700
Median gross rent$1,963This ZIP$1,963Texas$1,403US $1,413
Bachelor's degree or higher58.0%This ZIP58.0%
Mean commute23.6 minThis ZIP23.6 min
Population density2,444.7 / sq miThis ZIP2,444.7 / sq mi

Business and tax activity

Business establishments1,432This ZIP1,432
Employees19,609This ZIP19,609
Annual payroll$1,265,360,000This ZIP$1,265,360,000
Tax returns filed25,410This ZIP25,410
Total adjusted gross income$3,352,853,000This ZIP$3,352,853,000

Land area

Land area23.19 sq miThis ZIP23.19 sq mi
Water area0.14 sq miThis ZIP0.14 sq mi

Other place names in 78681

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

ZIP codes near 78681

ZIPCityDistance
78717 Austin, TX 4.2 mi
78665 Round Rock, TX 4.8 mi
78664 Round Rock, TX 4.8 mi
78729 Austin, TX 6.3 mi
78728 Austin, TX 6.3 mi
78613 Cedar Park, TX 6.6 mi
78630 Cedar Park, TX 6.7 mi
78627 Georgetown, TX 6.7 mi
78764 Austin, TX 7.5 mi
78727 Austin, TX 7.8 mi

Find every ZIP code within 10 miles of 78681 →

Questions about this ZIP code

Where is ZIP code 78681?

78681 is in Round Rock, Texas, in Williamson County, part of the Austin-Round Rock-San Marcos, TX metropolitan area. Its published point location is 30.5418, -97.7166.

What county is 78681 in?

78681 lies in Williamson County.

What area code is 78681?

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

What time zone is 78681 in?

78681 uses America/Chicago.

How many people live in 78681?

About 56,691 people live in ZIP code 78681, in 20,135 households, at 2,444.7 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 78681?

$137,819 a year, against $78,476 across Texas.

What ZIP codes are near 78681?

The closest are 78717 (4.2 mi), 78665 (4.8 mi), 78664 (4.8 mi), 78729 (6.3 mi) and 78728 (6.3 mi).

Is 78681 a PO Box ZIP code?

78681 is a standard ZIP code. A normal ZIP code with street delivery.

Download or cite

Cite this page

zipcodes.pro. “78681 ZIP Code — Round Rock, Texas (Williamson County).” Data release 2026-10-12. Retrieved 2026-10-20. https://zipcodes.pro/zip/78681

Machine-readable version of these facts:

curl https://zipcodes.pro/zip/78681.json

Underlying data is public domain or openly licensed — sources, vintages and licences.