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Where 21010 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 21010 into a pocket calculator and turn it upside down: OIOIZ — not quite a word, sorry.
- ➕ As a number, 21,010 = 2 × 5 × 11 × 191. Its digits add up to 4, a total 27 other ZIP codes share.
- 💾In binary, the way a computer stores it:
101001000010010 - 🏠 Its numerical neighbours: 21009 (Abingdon, MD, 6 mi away) and 21012 (Arnold, MD, 26 mi away).
- 🔄 Backwards, 21010 becomes 01012 — and that is a real ZIP code: Chesterfield, MA, 273 miles away.
- 👥 16 other ZIP codes are made of exactly the same digits (01012, 01021, 01102, 01201, 02110, 10012, …). The farthest-flung twin is 02110 in Boston, MA, 342 miles away.
- 🧭 Farther north than 52% of all ZIP codes, and farther east than 84%.
- 🎯1,184 miles east of the geographic center of the Lower 48, near Lebanon, Kansas.
- 🌏 Dig straight through the Earth from 21010 and you would come out at 39.39°S, 103.71°E — 853 miles from Perth, Australia, the nearest big city to that spot.
- ☀Longest day of the year: 14h 57m of daylight. Shortest: 9h 23m.
- 📏 At 7.3 square miles of land, 21010 is bigger than 23% of ZIP codes — room for about 5.5 Central Parks.
- Working out the sun…
- Checking the USGS…
Source: USGS.
People and housing
| Population | 239This ZIP239 |
|---|---|
| Households | 55This ZIP55 |
| Housing units | 117This ZIP117 |
| Median age | 19.3This ZIP19.3Maryland39.4US 38.9 |
| Median household income | $99,410This ZIP$99,410Maryland$103,678US $80,734 |
| Median gross rent | $3,147This ZIP$3,147Maryland$1,705US $1,413 |
| Bachelor's degree or higher | 69.3%This ZIP69.3% |
| Population density | 33.0 / sq miThis ZIP33.0 / sq mi |
Business and tax activity
| Business establishments | 18This ZIP18 |
|---|---|
| Employees | 1,165This ZIP1,165 |
| Annual payroll | $57,054,000This ZIP$57,054,000 |
Land area
| Land area | 7.25 sq miThis ZIP7.25 sq mi |
|---|---|
| Water area | 0.05 sq miThis ZIP0.05 sq mi |
Other place names in 21010
Census places whose land this ZIP code overlaps. The Postal Service may accept other city names in an address, too.
ZIP codes near 21010
| ZIP | City | Distance |
|---|---|---|
21040 | Edgewood, MD | 2.7 mi |
21027 | Chase, MD | 4.6 mi |
21085 | Joppa, MD | 5.1 mi |
21009 | Abingdon, MD | 5.6 mi |
21162 | White Marsh, MD | 6.0 mi |
21220 | Middle River, MD | 6.2 mi |
21156 | Upper Falls, MD | 6.5 mi |
21017 | Belcamp, MD | 6.6 mi |
21087 | Kingsville, MD | 7.6 mi |
21130 | Perryman, MD | 8.0 mi |
Find every ZIP code within 10 miles of 21010 →
Questions about this ZIP code
Where is ZIP code 21010?
21010 is in Gunpowder, Maryland, in Harford County, part of the Baltimore-Columbia-Towson, MD metropolitan area. Its published point location is 39.3909, -76.2926.
What county is 21010 in?
21010 lies in Harford County.
What area code is 21010?
Gunpowder uses area codes 443, 410 and 667, from NANPA's telephone records.
What time zone is 21010 in?
21010 uses America/New_York.
How many people live in 21010?
About 239 people live in ZIP code 21010, in 55 households, at 33.0 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 21010?
$99,410 a year, against $103,678 across Maryland.
What ZIP codes are near 21010?
The closest are 21040 (2.7 mi), 21027 (4.6 mi), 21085 (5.1 mi), 21009 (5.6 mi) and 21162 (6 mi).
Is 21010 a PO Box ZIP code?
21010 is a standard ZIP code. A normal ZIP code with street delivery.
Download or cite
Cite this page
zipcodes.pro. “21010 ZIP Code — Gunpowder, Maryland (Harford County).” Data release 2026-10-12. Retrieved 2026-10-20. https://zipcodes.pro/zip/21010
Machine-readable version of these facts:
curl https://zipcodes.pro/zip/21010.jsonUnderlying data is public domain or openly licensed — sources, vintages and licences.