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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/78521

78521

ZIP 78521 is in Brownsville, Texas, in Cameron County; area code 956; Central time. Brownsville has 5 ZIP codes; the others are 78520, 78522, 78523 and 78526.

Type
Standard
Time zone
America/Chicago
County
Cameron
Population
87,380
Coordinates
25.9439, -97.3179
☼ Live from 78521 — Brownsville, TX

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Where 78521 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 78521
  • 🔢 Type 78521 into a pocket calculator and turn it upside down: IZSBL — not quite a word, sorry.
  • ➕ As a number, 78,521 = 233 × 337. Its digits add up to 23, a total 2,533 other ZIP codes share.
  • 💾In binary, the way a computer stores it: 10011001010111001
  • 🏠 Its numerical neighbours: 78520 (Brownsville, TX, 14 mi away) and 78522 (Brownsville, TX, 12 mi away).
  • 🔄 Backwards, 78521 becomes 12587, which is not a ZIP code at all.
  • 👥 48 other ZIP codes are made of exactly the same digits (12578, 12758, 12785, 12857, 15278, 15728, …). The farthest-flung twin is 12857 in Olmstedville, NY, 1,800 miles away.
  • 🧭 Farther south than 98% of all ZIP codes, and farther west than 75%.
  • 🎯962 miles south of the geographic center of the Lower 48, near Lebanon, Kansas.
  • 🌏 Dig straight through the Earth from 78521 and you would come out at 25.94°S, 82.68°E — 1,324 miles from West Island, Cocos Islands, the nearest big city to that spot.
  • ☀Longest day of the year: 13h 46m of daylight. Shortest: 10h 31m.
  • 📏 At 93.6 square miles of land, 78521 is bigger than 76% of ZIP codes — room for about 71 Central Parks.
🌙 The sky over 78521 today
  • Working out the sun…
🌋 Shake report
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Source: USGS.

People and housing

Population87,380This ZIP87,380
Households27,731This ZIP27,731
Housing units29,741This ZIP29,741
Median age31.3This ZIP31.3Texas35.6US 38.9
Median household income$44,509This ZIP$44,509Texas$78,476US $80,734
Median home value$99,700This ZIP$99,700Texas$283,800US $332,700
Median gross rent$889This ZIP$889Texas$1,403US $1,413
Bachelor's degree or higher16.7%This ZIP16.7%
Mean commute22.4 minThis ZIP22.4 min
Population density933.3 / sq miThis ZIP933.3 / sq mi

Business and tax activity

Business establishments1,384This ZIP1,384
Employees28,048This ZIP28,048
Annual payroll$1,209,154,000This ZIP$1,209,154,000
Tax returns filed38,820This ZIP38,820
Total adjusted gross income$1,577,710,000This ZIP$1,577,710,000

Land area

Land area93.62 sq miThis ZIP93.62 sq mi
Water area27.93 sq miThis ZIP27.93 sq mi

Other place names in 78521

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

ZIP codes near 78521

ZIPCityDistance
78578 Port Isabel, TX 6.9 mi
78526 Brownsville, TX 9.0 mi
78522 Brownsville, TX 11.5 mi
78523 Brownsville, TX 12.9 mi
78566 Los Fresnos, TX 14.1 mi
78520 Brownsville, TX 14.4 mi
78575 Olmito, TX 15.7 mi
78568 Lozano, TX 22.0 mi
78597 South Padre Island, TX 22.9 mi
78586 San Benito, TX 23.3 mi

Find every ZIP code within 10 miles of 78521 →

Questions about this ZIP code

Where is ZIP code 78521?

78521 is in Brownsville, Texas, in Cameron County, part of the Brownsville-Harlingen, TX metropolitan area. Its published point location is 25.9439, -97.3179.

What county is 78521 in?

78521 lies in Cameron County.

What area code is 78521?

Brownsville uses area code 956, from NANPA's telephone records.

What time zone is 78521 in?

78521 uses America/Chicago.

How many people live in 78521?

About 87,380 people live in ZIP code 78521, in 27,731 households, at 933.3 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 78521?

$44,509 a year, against $78,476 across Texas.

What ZIP codes are near 78521?

The closest are 78578 (6.9 mi), 78526 (9 mi), 78522 (11.5 mi), 78523 (12.9 mi) and 78566 (14.1 mi).

Is 78521 a PO Box ZIP code?

78521 is a standard ZIP code. A normal ZIP code with street delivery.

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Cite this page

zipcodes.pro. “78521 ZIP Code — Brownsville, Texas (Cameron County).” Data release 2026-10-12. Retrieved 2026-10-20. https://zipcodes.pro/zip/78521

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