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Where 21738 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 21738 into a pocket calculator and turn it upside down: BELIZ — not quite a word, sorry.
- ➕ As a number, 21,738 = 2 × 3 × 3623. Its digits add up to 21, a total 2,594 other ZIP codes share.
- 💾In binary, the way a computer stores it:
101010011101010 - 🏠 Its numerical neighbours: 21737 (Glenelg, MD, 2 mi away) and 21740 (Hagerstown, MD, 45 mi away).
- 🔄 Backwards, 21738 becomes 83712 — and that is a real ZIP code: Boise, ID, 2,026 miles away.
- 👥 56 other ZIP codes are made of exactly the same digits (12738, 12783, 12837, 12873, 13782, 13827, …). The farthest-flung twin is 83712 in Boise, ID, 2,026 miles away.
- 🧭 Farther north than 51% of all ZIP codes, and farther east than 81%.
- 🎯1,146 miles east of the geographic center of the Lower 48, near Lebanon, Kansas.
- 🌏 Dig straight through the Earth from 21738 and you would come out at 39.28°S, 102.97°E — 882 miles from Perth, Australia, the nearest big city to that spot.
- ☀Longest day of the year: 14h 56m of daylight. Shortest: 9h 24m.
- 📏 At 7.0 square miles of land, 21738 is bigger than 22% of ZIP codes — room for about 5.3 Central Parks.
- Working out the sun…
- Checking the USGS…
Source: USGS.
People and housing
| Population | 3,696This ZIP3,696 |
|---|---|
| Households | 1,121This ZIP1,121 |
| Housing units | 1,121This ZIP1,121 |
| Median age | 41.2This ZIP41.2Maryland39.4US 38.9 |
| Median household income | $250,000+This ZIP$250,000+Maryland$103,678US $80,734 |
| Median home value | $914,300This ZIP$914,300Maryland$419,900US $332,700 |
| Bachelor's degree or higher | 76.2%This ZIP76.2% |
| Mean commute | 33.9 minThis ZIP33.9 min |
| Population density | 529.5 / sq miThis ZIP529.5 / sq mi |
Business and tax activity
| Business establishments | 91This ZIP91 |
|---|---|
| Employees | 729This ZIP729 |
| Annual payroll | $55,281,000This ZIP$55,281,000 |
| Tax returns filed | 1,660This ZIP1,660 |
| Total adjusted gross income | $460,621,000This ZIP$460,621,000 |
Land area
| Land area | 6.98 sq miThis ZIP6.98 sq mi |
|---|---|
| Water area | 0.04 sq miThis ZIP0.04 sq mi |
ZIP codes near 21738
| ZIP | City | Distance |
|---|---|---|
21737 | Glenelg, MD | 2.2 mi |
21036 | Dayton, MD | 3.3 mi |
21794 | West Friendship, MD | 3.5 mi |
21723 | Cooksville, MD | 3.6 mi |
21797 | Woodbine, MD | 4.2 mi |
21765 | Lisbon, MD | 4.7 mi |
20833 | Brookeville, MD | 5.2 mi |
21041 | Ellicott City, MD | 5.4 mi |
21150 | Simpsonville, MD | 5.4 mi |
21029 | Clarksville, MD | 5.8 mi |
Find every ZIP code within 10 miles of 21738 →
Questions about this ZIP code
Where is ZIP code 21738?
21738 is in Glenwood, Maryland, in Howard County, part of the Baltimore-Columbia-Towson, MD metropolitan area. Its published point location is 39.2798, -77.0267.
What county is 21738 in?
21738 lies in Howard County.
What area code is 21738?
Glenwood uses area codes 443, 667 and 410, from NANPA's telephone records.
What time zone is 21738 in?
21738 uses America/New_York.
How many people live in 21738?
About 3,696 people live in ZIP code 21738, in 1,121 households, at 529.5 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 21738?
$250,000+ a year, against $103,678 across Maryland.
What ZIP codes are near 21738?
The closest are 21737 (2.2 mi), 21036 (3.3 mi), 21794 (3.5 mi), 21723 (3.6 mi) and 21797 (4.2 mi).
Is 21738 a PO Box ZIP code?
21738 is a standard ZIP code. A normal ZIP code with street delivery.
Download or cite
Cite this page
zipcodes.pro. “21738 ZIP Code — Glenwood, Maryland (Howard County).” Data release 2026-10-12. Retrieved 2026-10-20. https://zipcodes.pro/zip/21738
Machine-readable version of these facts:
curl https://zipcodes.pro/zip/21738.jsonUnderlying data is public domain or openly licensed — sources, vintages and licences.