Weather right now
Asking the National Weather Service…
Where 21758 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 21758 into a pocket calculator and turn it upside down: BSLIZ — not quite a word, sorry.
- ➕ As a number, 21,758 = 2 × 11 × 23 × 43. Its digits add up to 23, a total 2,533 other ZIP codes share.
- 💾In binary, the way a computer stores it:
101010011111110 - 🏠 Its numerical neighbours: 21757 (Keymar, MD, 27 mi away) and 21759 (Ladiesburg, MD, 25 mi away).
- 🔄 Backwards, 21758 becomes 85712 — and that is a real ZIP code: Tucson, AZ, 1,914 miles away.
- 👥 48 other ZIP codes are made of exactly the same digits (12578, 12758, 12785, 12857, 15278, 15728, …). The farthest-flung twin is 85172 in Stanfield, AZ, 1,953 miles away.
- 🧭 Farther north than 51% of all ZIP codes, and farther east than 79%.
- 🎯1,112 miles east of the geographic center of the Lower 48, near Lebanon, Kansas.
- 🌏 Dig straight through the Earth from 21758 and you would come out at 39.35°S, 102.34°E — 914 miles from Perth, Australia, the nearest big city to that spot.
- ☀Longest day of the year: 14h 57m of daylight. Shortest: 9h 23m.
- 📏 At 32.0 square miles of land, 21758 is bigger than 47% of ZIP codes — room for about 24 Central Parks.
- Working out the sun…
- Checking the USGS…
Source: USGS.
People and housing
| Population | 4,409This ZIP4,409 |
|---|---|
| Households | 1,588This ZIP1,588 |
| Housing units | 1,626This ZIP1,626 |
| Median age | 39.0This ZIP39.0Maryland39.4US 38.9 |
| Median household income | $111,528This ZIP$111,528Maryland$103,678US $80,734 |
| Median home value | $424,600This ZIP$424,600Maryland$419,900US $332,700 |
| Median gross rent | $1,770This ZIP$1,770Maryland$1,705US $1,413 |
| Bachelor's degree or higher | 43.7%This ZIP43.7% |
| Mean commute | 36.1 minThis ZIP36.1 min |
| Population density | 137.7 / sq miThis ZIP137.7 / sq mi |
Business and tax activity
| Business establishments | 59This ZIP59 |
|---|---|
| Employees | 402This ZIP402 |
| Annual payroll | $16,270,000This ZIP$16,270,000 |
| Tax returns filed | 2,340This ZIP2,340 |
| Total adjusted gross income | $219,170,000This ZIP$219,170,000 |
Land area
| Land area | 32.02 sq miThis ZIP32.02 sq mi |
|---|---|
| Water area | 2.83 sq miThis ZIP2.83 sq mi |
Counties 21758 spans
A ZIP code is a mail route and ignores county lines. Shares are by overlapping land area.
| County | Share of this ZIP |
|---|---|
| Frederick County | 50.3% |
| Washington County | 49.7% |
Other place names in 21758
Census places whose land this ZIP code overlaps. The Postal Service may accept other city names in an address, too.
ZIP codes near 21758
| ZIP | City | Distance |
|---|---|---|
21715 | Brownsville, MD | 1.8 mi |
21716 | Brunswick, MD | 2.9 mi |
21718 | Burkittsville, MD | 3.2 mi |
21755 | Jefferson, MD | 4.8 mi |
21779 | Rohrersville, MD | 4.9 mi |
20180 | Lovettsville, VA | 5.9 mi |
25425 | Harpers Ferry, WV | 7.0 mi |
21756 | Keedysville, MD | 7.6 mi |
21769 | Middletown, MD | 7.8 mi |
25423 | Halltown, WV | 8.0 mi |
Find every ZIP code within 10 miles of 21758 →
Questions about this ZIP code
Where is ZIP code 21758?
21758 is in Knoxville, Maryland, in Frederick County, part of the Washington-Arlington-Alexandria, DC-VA-MD-WV metropolitan area. Its published point location is 39.3532, -77.6568.
What county is 21758 in?
21758 spans 2 counties: Frederick County and Washington County. Most of it falls in Frederick County, measured by overlapping land area — the county holding the most land in a ZIP code is not always the one holding the most residents.
What area code is 21758?
Knoxville uses area codes 240, 301 and 227, from NANPA's telephone records.
What time zone is 21758 in?
21758 uses America/New_York.
How many people live in 21758?
About 4,409 people live in ZIP code 21758, in 1,588 households, at 137.7 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 21758?
$111,528 a year, against $103,678 across Maryland.
What ZIP codes are near 21758?
The closest are 21715 (1.8 mi), 21716 (2.9 mi), 21718 (3.2 mi), 21755 (4.8 mi) and 21779 (4.9 mi).
Is 21758 a PO Box ZIP code?
21758 is a standard ZIP code. A normal ZIP code with street delivery.
Download or cite
Cite this page
zipcodes.pro. “21758 ZIP Code — Knoxville, Maryland (Frederick County).” Data release 2026-10-12. Retrieved 2026-10-20. https://zipcodes.pro/zip/21758
Machine-readable version of these facts:
curl https://zipcodes.pro/zip/21758.jsonUnderlying data is public domain or openly licensed — sources, vintages and licences.