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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/21128

21128

ZIP 21128 is Perry Hall, Maryland, in Baltimore County; area codes 410, 443 and 667; Eastern time.

Type
Standard
Time zone
America/New_York
County
Baltimore
Population
15,501
Coordinates
39.4047, -76.4482
☼ Live from 21128 — Perry Hall, MD

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Local time: —

Where 21128 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 21128
  • 🔢 Type 21128 into a pocket calculator and turn it upside down: BZIIZ — not quite a word, sorry.
  • ➕ As a number, 21,128 = 2 × 2 × 2 × 19 × 139. Its digits add up to 14, a total 1,416 other ZIP codes share.
  • 💾In binary, the way a computer stores it: 101001010001000
  • 🏠 Its numerical neighbours: 21123 (Pasadena, MD, 31 mi away) and 21130 (Perryman, MD, 15 mi away).
  • 🔄 Backwards, 21128 becomes 82112, which is not a ZIP code at all.
  • 👥 18 other ZIP codes are made of exactly the same digits (11228, 12128, 12182, 12812, 12821, 18212, …). The farthest-flung twin is 81122 in Bayfield, CO, 1,682 miles away.
  • 🧭 Farther north than 52% of all ZIP codes, and farther east than 84%.
  • 🎯1,175 miles east of the geographic center of the Lower 48, near Lebanon, Kansas.
  • 🌏 Dig straight through the Earth from 21128 and you would come out at 39.40°S, 103.55°E — 860 miles from Perth, Australia, the nearest big city to that spot.
  • ☀Longest day of the year: 14h 57m of daylight. Shortest: 9h 23m.
  • 📏 At 6.8 square miles of land, 21128 is bigger than 22% of ZIP codes — room for about 5.2 Central Parks.
🌙 The sky over 21128 today
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🌋 Shake report
  • Checking the USGS…

Source: USGS.

People and housing

Population15,501This ZIP15,501
Households5,609This ZIP5,609
Housing units5,917This ZIP5,917
Median age40.1This ZIP40.1Maryland39.4US 38.9
Median household income$128,069This ZIP$128,069Maryland$103,678US $80,734
Median home value$449,500This ZIP$449,500Maryland$419,900US $332,700
Median gross rent$1,935This ZIP$1,935Maryland$1,705US $1,413
Bachelor's degree or higher54.8%This ZIP54.8%
Mean commute33.2 minThis ZIP33.2 min
Population density2,277.2 / sq miThis ZIP2,277.2 / sq mi

Business and tax activity

Business establishments223This ZIP223
Employees2,023This ZIP2,023
Annual payroll$82,766,000This ZIP$82,766,000
Tax returns filed7,730This ZIP7,730
Total adjusted gross income$853,813,000This ZIP$853,813,000

Land area

Land area6.81 sq miThis ZIP6.81 sq mi
Water area0.01 sq miThis ZIP0.01 sq mi

Other place names in 21128

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

ZIP codes near 21128

ZIPCityDistance
21236 Nottingham, MD 2.2 mi
21162 White Marsh, MD 2.5 mi
21156 Upper Falls, MD 2.9 mi
21087 Kingsville, MD 3.6 mi
21234 Parkville, MD 4.5 mi
21057 Glen Arm, MD 4.6 mi
21051 Fork, MD 4.7 mi
21027 Chase, MD 5.0 mi
21237 Rosedale, MD 5.0 mi
21220 Middle River, MD 5.2 mi

Find every ZIP code within 10 miles of 21128 →

Questions about this ZIP code

Where is ZIP code 21128?

21128 is in Perry Hall, Maryland, in Baltimore County, part of the Baltimore-Columbia-Towson, MD metropolitan area. Its published point location is 39.4047, -76.4482.

What county is 21128 in?

21128 lies in Baltimore County.

What area code is 21128?

Perry Hall uses area codes 410, 443 and 667, from NANPA's telephone records.

What time zone is 21128 in?

21128 uses America/New_York.

How many people live in 21128?

About 15,501 people live in ZIP code 21128, in 5,609 households, at 2,277.2 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 21128?

$128,069 a year, against $103,678 across Maryland.

What ZIP codes are near 21128?

The closest are 21236 (2.2 mi), 21162 (2.5 mi), 21156 (2.9 mi), 21087 (3.6 mi) and 21234 (4.5 mi).

Is 21128 a PO Box ZIP code?

21128 is a standard ZIP code. A normal ZIP code with street delivery.

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Cite this page

zipcodes.pro. “21128 ZIP Code — Perry Hall, Maryland (Baltimore County).” Data release 2026-10-12. Retrieved 2026-10-20. https://zipcodes.pro/zip/21128

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