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Where 21640 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 21640 into a pocket calculator and turn it upside down: OhgIZ — not quite a word, sorry.
- ➕ As a number, 21,640 = 2 × 2 × 2 × 5 × 541. Its digits add up to 13, a total 1,179 other ZIP codes share.
- 💾In binary, the way a computer stores it:
101010010001000 - 🏠 Its numerical neighbours: 21639 (Greensboro, MD, 8 mi away) and 21641 (Hillsboro, MD, 12 mi away).
- 🔄 Backwards, 21640 becomes 04612 — and that is a real ZIP code: Bernard, ME, 525 miles away.
- 👥 66 other ZIP codes are made of exactly the same digits (01264, 01462, 02461, 02641, 04216, 04261, …). The farthest-flung twin is 64102 in Kansas City, MO, 1,006 miles away.
- 🧭 Farther south than 50% of all ZIP codes, and farther east than 85%.
- 🎯1,212 miles east of the geographic center of the Lower 48, near Lebanon, Kansas.
- 🌏 Dig straight through the Earth from 21640 and you would come out at 39.07°S, 104.18°E — 819 miles from Perth, Australia, the nearest big city to that spot.
- ☀Longest day of the year: 14h 55m of daylight. Shortest: 9h 25m.
- 📏 At 25.7 square miles of land, 21640 is bigger than 42% of ZIP codes — room for about 19 Central Parks.
- Working out the sun…
- Checking the USGS…
Source: USGS.
People and housing
| Population | 1,163This ZIP1,163 |
|---|---|
| Households | 511This ZIP511 |
| Housing units | 531This ZIP531 |
| Median age | 39.9This ZIP39.9Maryland39.4US 38.9 |
| Median household income | $53,558This ZIP$53,558Maryland$103,678US $80,734 |
| Median home value | $268,500This ZIP$268,500Maryland$419,900US $332,700 |
| Bachelor's degree or higher | 13.9%This ZIP13.9% |
| Mean commute | 36.0 minThis ZIP36.0 min |
| Population density | 45.3 / sq miThis ZIP45.3 / sq mi |
Business and tax activity
| Business establishments | 11This ZIP11 |
|---|---|
| Employees | 65This ZIP65 |
| Annual payroll | $1,986,000This ZIP$1,986,000 |
| Tax returns filed | 750This ZIP750 |
| Total adjusted gross income | $46,786,000This ZIP$46,786,000 |
Land area
| Land area | 25.66 sq miThis ZIP25.66 sq mi |
|---|---|
| Water area | 0.08 sq miThis ZIP0.08 sq mi |
Counties 21640 spans
A ZIP code is a mail route and ignores county lines. Shares are by overlapping land area.
| County | Share of this ZIP |
|---|---|
| Caroline County | 80.2% |
| Queen Anne's County | 19.8% |
Other place names in 21640
Census places whose land this ZIP code overlaps. The Postal Service may accept other city names in an address, too.
ZIP codes near 21640
| ZIP | City | Distance |
|---|---|---|
21636 | Goldsboro, MD | 3.9 mi |
21644 | Ingleside, MD | 4.4 mi |
21607 | Barclay, MD | 4.9 mi |
19964 | Marydel, DE | 5.5 mi |
21670 | Templeville, MD | 5.5 mi |
21649 | Marydel, MD | 5.7 mi |
21639 | Greensboro, MD | 7.8 mi |
21660 | Ridgely, MD | 8.6 mi |
21668 | Sudlersville, MD | 8.6 mi |
21623 | Church Hill, MD | 8.7 mi |
Find every ZIP code within 10 miles of 21640 →
Questions about this ZIP code
Where is ZIP code 21640?
21640 is in Henderson, Maryland, in Caroline County. Its published point location is 39.0681, -75.8209.
What county is 21640 in?
21640 spans 2 counties: Caroline County and Queen Anne's County. Most of it falls in Caroline 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 21640?
Henderson uses area codes 667 and 410, from NANPA's telephone records.
What time zone is 21640 in?
21640 uses America/New_York.
How many people live in 21640?
About 1,163 people live in ZIP code 21640, in 511 households, at 45.3 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 21640?
$53,558 a year, against $103,678 across Maryland.
What ZIP codes are near 21640?
The closest are 21636 (3.9 mi), 21644 (4.4 mi), 21607 (4.9 mi), 19964 (5.5 mi) and 21670 (5.5 mi).
Is 21640 a PO Box ZIP code?
21640 is a standard ZIP code. A normal ZIP code with street delivery.
Download or cite
Cite this page
zipcodes.pro. “21640 ZIP Code — Henderson, Maryland (Caroline County).” Data release 2026-10-12. Retrieved 2026-10-20. https://zipcodes.pro/zip/21640
Machine-readable version of these facts:
curl https://zipcodes.pro/zip/21640.jsonUnderlying data is public domain or openly licensed — sources, vintages and licences.