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/78663

78663

ZIP 78663 is Round Mountain, Texas, mostly in Blanco County; area code 830; Central time.

Type
Standard
Time zone
America/Chicago
County
Blanco +3 more
Metro area
none
Population
503
Coordinates
30.4155, -98.3117
☼ Live from 78663 — Round Mountain, TX

Weather right now

Asking the National Weather Service…

NEXRAD radar
Finding the nearest radar…
Local time: —

Where 78663 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 78663
  • 🔢 Type 78663 into a pocket calculator and turn it upside down: EggBL — not quite a word, sorry.
  • ➕ As a number, 78,663 = 3 × 13 × 2017. Its digits add up to 30, a total 1,024 other ZIP codes share.
  • 💾In binary, the way a computer stores it: 10011001101000111
  • 🏠 Its numerical neighbours: 78662 (Red Rock, TX, 61 mi away) and 78664 (Round Rock, TX, 40 mi away).
  • 🔄 Backwards, 78663 becomes 36687, which is not a ZIP code at all.
  • 👥 24 other ZIP codes are made of exactly the same digits (36768, 36786, 36867, 37686, 37866, 38676, …). The farthest-flung twin is 83676 in Wilder, ID, 1,368 miles away.
  • 🧭 Farther south than 92% of all ZIP codes, and farther west than 77%.
  • 🎯651 miles south of the geographic center of the Lower 48, near Lebanon, Kansas.
  • 🌏 Dig straight through the Earth from 78663 and you would come out at 30.42°S, 81.69°E — 1,439 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 11m.
  • 📏 At 108.5 square miles of land, 78663 is bigger than 80% of ZIP codes — room for about 82 Central Parks.
🌙 The sky over 78663 today
  • Working out the sun…
🌋 Shake report
  • Checking the USGS…

Source: USGS.

People and housing

Population503This ZIP503
Households276This ZIP276
Housing units288This ZIP288
Median age65.4This ZIP65.4Texas35.6US 38.9
Median household income$168,125This ZIP$168,125Texas$78,476US $80,734
Median home value$356,800This ZIP$356,800Texas$283,800US $332,700
Median gross rent$1,688This ZIP$1,688Texas$1,403US $1,413
Bachelor's degree or higher42.7%This ZIP42.7%
Mean commute50.5 minThis ZIP50.5 min
Population density4.6 / sq miThis ZIP4.6 / sq mi

Business and tax activity

Business establishments32This ZIP32
Employees134This ZIP134
Annual payroll$12,020,000This ZIP$12,020,000
Tax returns filed470This ZIP470
Total adjusted gross income$73,041,000This ZIP$73,041,000

Land area

Land area108.48 sq miThis ZIP108.48 sq mi
Water area0.64 sq miThis ZIP0.64 sq mi

Counties 78663 spans

A ZIP code is a mail route and ignores county lines. Shares are by overlapping land area.

CountyShare of this ZIP
Blanco County 93.3%
Travis County 3.8%
Hays County 2.0%
Burnet County 0.9%

Other place names in 78663

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

ZIP codes near 78663

ZIPCityDistance
78657 Horseshoe Bay, TX 9.1 mi
78636 Johnson City, TX 9.6 mi
78669 Spicewood, TX 11.4 mi
78654 Marble Falls, TX 12.4 mi
78620 Dripping Springs, TX 16.8 mi
78639 Kingsland, TX 18.7 mi
78635 Hye, TX 20.1 mi
78645 Leander, TX 20.4 mi
78738 Austin, TX 20.7 mi
78734 Austin, TX 21.8 mi

Find every ZIP code within 10 miles of 78663 →

Questions about this ZIP code

Where is ZIP code 78663?

78663 is in Round Mountain, Texas, in Blanco County. Its published point location is 30.4155, -98.3117.

What county is 78663 in?

78663 spans 4 counties: Blanco County, Travis County, Hays County and Burnet County. Most of it falls in Blanco County, measured by overlapping land area — the county holding the most land in a ZIP code is not always the one holding the most residents.

What area code is 78663?

Round Mountain uses area code 830, from NANPA's telephone records.

What time zone is 78663 in?

78663 uses America/Chicago.

How many people live in 78663?

About 503 people live in ZIP code 78663, in 276 households, at 4.6 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 78663?

$168,125 a year, against $78,476 across Texas.

What ZIP codes are near 78663?

The closest are 78657 (9.1 mi), 78636 (9.6 mi), 78669 (11.4 mi), 78654 (12.4 mi) and 78620 (16.8 mi).

Is 78663 a PO Box ZIP code?

78663 is a standard ZIP code. A normal ZIP code with street delivery.

Download or cite

Cite this page

zipcodes.pro. “78663 ZIP Code — Round Mountain, Texas (Blanco County).” Data release 2026-10-12. Retrieved 2026-10-20. https://zipcodes.pro/zip/78663

Machine-readable version of these facts:

curl https://zipcodes.pro/zip/78663.json

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