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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/21042

21042

ZIP 21042 is in Ellicott City, Maryland, in Howard County; area codes 410, 443 and 667; Eastern time. Ellicott City has 3 ZIP codes; the others are 21041 and 21043.

Type
Standard
Time zone
America/New_York
County
Howard
Population
43,327
Coordinates
39.2772, -76.8946
☼ Live from 21042 — Ellicott City, MD

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Where 21042 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 21042
  • 🔢 Type 21042 into a pocket calculator and turn it upside down: ZhOIZ — not quite a word, sorry.
  • ➕ As a number, 21,042 = 2 × 3 × 3 × 7 × 167. Its digits add up to 9, a total 375 other ZIP codes share.
  • 💾In binary, the way a computer stores it: 101001000110010
  • 🏠 Its numerical neighbours: 21041 (Ellicott City, MD, 4 mi away) and 21043 (Ellicott City, MD, 5 mi away).
  • 🔄 Backwards, 21042 becomes 24012 — and that is a real ZIP code: Roanoke, VA, 212 miles away.
  • 👥 43 other ZIP codes are made of exactly the same digits (01224, 01242, 02124, 02142, 02241, 02421, …). The farthest-flung twin is 42021 in Arlington, KY, 680 miles away.
  • 🧭 Farther north than 51% of all ZIP codes, and farther east than 82%.
  • 🎯1,153 miles east of the geographic center of the Lower 48, near Lebanon, Kansas.
  • 🌏 Dig straight through the Earth from 21042 and you would come out at 39.28°S, 103.11°E — 876 miles from Perth, Australia, the nearest big city to that spot.
  • ☀Longest day of the year: 14h 56m of daylight. Shortest: 9h 24m.
  • 📏 At 37.0 square miles of land, 21042 is bigger than 51% of ZIP codes — room for about 28 Central Parks.
🌙 The sky over 21042 today
  • Working out the sun…
🌋 Shake report
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Source: USGS.

People and housing

Population43,327This ZIP43,327
Households15,099This ZIP15,099
Housing units15,368This ZIP15,368
Median age45.1This ZIP45.1Maryland39.4US 38.9
Median household income$190,061This ZIP$190,061Maryland$103,678US $80,734
Median home value$706,400This ZIP$706,400Maryland$419,900US $332,700
Median gross rent$2,183This ZIP$2,183Maryland$1,705US $1,413
Bachelor's degree or higher72.9%This ZIP72.9%
Mean commute28.6 minThis ZIP28.6 min
Population density1,171.0 / sq miThis ZIP1,171.0 / sq mi

Business and tax activity

Business establishments1,194This ZIP1,194
Employees9,947This ZIP9,947
Annual payroll$511,873,000This ZIP$511,873,000
Tax returns filed20,610This ZIP20,610
Total adjusted gross income$3,690,260,000This ZIP$3,690,260,000

Land area

Land area37.00 sq miThis ZIP37.00 sq mi
Water area0.17 sq miThis ZIP0.17 sq mi

Other place names in 21042

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

ZIP codes near 21042

ZIPCityDistance
21041 Ellicott City, MD 3.8 mi
21150 Simpsonville, MD 3.8 mi
21794 West Friendship, MD 4.1 mi
21163 Woodstock, MD 4.9 mi
21104 Marriottsville, MD 4.9 mi
21044 Columbia, MD 5.0 mi
21043 Ellicott City, MD 5.2 mi
21029 Clarksville, MD 5.6 mi
21045 Columbia, MD 6.1 mi
21036 Dayton, MD 6.7 mi

Find every ZIP code within 10 miles of 21042 →

Questions about this ZIP code

Where is ZIP code 21042?

21042 is in Ellicott City, Maryland, in Howard County, part of the Baltimore-Columbia-Towson, MD metropolitan area. Its published point location is 39.2772, -76.8946.

What county is 21042 in?

21042 lies in Howard County.

What area code is 21042?

Ellicott City uses area codes 410, 443 and 667, from NANPA's telephone records.

What time zone is 21042 in?

21042 uses America/New_York.

How many people live in 21042?

About 43,327 people live in ZIP code 21042, in 15,099 households, at 1,171.0 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 21042?

$190,061 a year, against $103,678 across Maryland.

What ZIP codes are near 21042?

The closest are 21041 (3.8 mi), 21150 (3.8 mi), 21794 (4.1 mi), 21163 (4.9 mi) and 21104 (4.9 mi).

Is 21042 a PO Box ZIP code?

21042 is a standard ZIP code. A normal ZIP code with street delivery.

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Cite this page

zipcodes.pro. “21042 ZIP Code — Ellicott City, Maryland (Howard County).” Data release 2026-10-12. Retrieved 2026-10-20. https://zipcodes.pro/zip/21042

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