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Where 78731 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.
- 🔢 Type 78731 into a pocket calculator and turn it upside down: IELBL — not quite a word, sorry.
- ➕ As a number, 78,731 = 131 × 601. Its digits add up to 26, a total 2,038 other ZIP codes share.
- 💾In binary, the way a computer stores it:
10011001110001011 - 🏠 Its numerical neighbours: 78730 (Austin, TX, 4 mi away) and 78732 (Austin, TX, 8 mi away).
- 🔄 Backwards, 78731 becomes 13787 — and that is a real ZIP code: Harpursville, NY, 1,472 miles away.
- 👥 24 other ZIP codes are made of exactly the same digits (13778, 13787, 17837, 18773, 31778, 31787, …). The farthest-flung twin is 13778 in Greene, NY, 1,472 miles away.
- 🧭 Farther south than 92% of all ZIP codes, and farther west than 76%.
- 🎯657 miles south of the geographic center of the Lower 48, near Lebanon, Kansas.
- 🌏 Dig straight through the Earth from 78731 and you would come out at 30.35°S, 82.23°E — 1,455 miles from Port-aux-Français, French Southern Territories, the nearest big city to that spot.
- ☀Longest day of the year: 14h 06m of daylight. Shortest: 10h 11m.
- 📏 At 8.7 square miles of land, 78731 is bigger than 25% of ZIP codes — room for about 6.6 Central Parks.
- Working out the sun…
- Checking the USGS…
Source: USGS.
People and housing
| Population | 27,507This ZIP27,507 |
|---|---|
| Households | 14,343This ZIP14,343 |
| Housing units | 15,163This ZIP15,163 |
| Median age | 42.3This ZIP42.3Texas35.6US 38.9 |
| Median household income | $105,494This ZIP$105,494Texas$78,476US $80,734 |
| Median home value | $903,200This ZIP$903,200Texas$283,800US $332,700 |
| Median gross rent | $1,737This ZIP$1,737Texas$1,403US $1,413 |
| Bachelor's degree or higher | 78.3%This ZIP78.3% |
| Mean commute | 20.9 minThis ZIP20.9 min |
| Population density | 3,145.1 / sq miThis ZIP3,145.1 / sq mi |
Business and tax activity
| Business establishments | 2,255This ZIP2,255 |
|---|---|
| Employees | 24,680This ZIP24,680 |
| Annual payroll | $1,850,666,000This ZIP$1,850,666,000 |
| Tax returns filed | 14,190This ZIP14,190 |
| Total adjusted gross income | $4,194,201,000This ZIP$4,194,201,000 |
Land area
| Land area | 8.75 sq miThis ZIP8.75 sq mi |
|---|---|
| Water area | 0.20 sq miThis ZIP0.20 sq mi |
Other place names in 78731
Census places whose land this ZIP code overlaps. The Postal Service may accept other city names in an address, too.
ZIP codes near 78731
| ZIP | City | Distance |
|---|---|---|
73301 | Austin, TX | 1.5 mi |
73344 | Austin, TX | 1.5 mi |
78651 | Mc Neil, TX | 1.5 mi |
78708 | Austin, TX | 1.5 mi |
78709 | Austin, TX | 1.5 mi |
78711 | Austin, TX | 1.5 mi |
78718 | Austin, TX | 1.5 mi |
78720 | Austin, TX | 1.5 mi |
78755 | Austin, TX | 1.5 mi |
78760 | Austin, TX | 1.5 mi |
Find every ZIP code within 10 miles of 78731 →
Questions about this ZIP code
Where is ZIP code 78731?
78731 is in Austin, Texas, in Travis County, part of the Austin-Round Rock-San Marcos, TX metropolitan area. Its published point location is 30.3482, -97.7681.
What county is 78731 in?
78731 lies in Travis County.
What area code is 78731?
Austin uses area codes 512 and 737, from NANPA's telephone records.
What time zone is 78731 in?
78731 uses America/Chicago.
How many people live in 78731?
About 27,507 people live in ZIP code 78731, in 14,343 households, at 3,145.1 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 78731?
$105,494 a year, against $78,476 across Texas.
What ZIP codes are near 78731?
The closest are 73301 (1.5 mi), 73344 (1.5 mi), 78651 (1.5 mi), 78708 (1.5 mi) and 78709 (1.5 mi).
Is 78731 a PO Box ZIP code?
78731 is a standard ZIP code. A normal ZIP code with street delivery.
Download or cite
Cite this page
zipcodes.pro. “78731 ZIP Code — Austin, Texas (Travis County).” Data release 2026-10-12. Retrieved 2026-10-20. https://zipcodes.pro/zip/78731
Machine-readable version of these facts:
curl https://zipcodes.pro/zip/78731.jsonUnderlying data is public domain or openly licensed — sources, vintages and licences.