21723
ZIP 21723 is Cooksville, Maryland, in Howard County; area codes 443, 667 and 410; Eastern time.
- Type
- Standard
- Time zone
- America/New_York
- County
- Howard
- Metro area
- Baltimore-Columbia-Towson, MD
- Population
- 669
- Coordinates
- 39.3291, -77.0026
Weather right now
Asking the National Weather Service…
Where 21723 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 21723 into a pocket calculator and turn it upside down: EZLIZ — not quite a word, sorry.
- ➕ As a number, 21,723 = 3 × 13 × 557. Its digits add up to 15, a total 1,657 other ZIP codes share.
- 💾In binary, the way a computer stores it:
101010011011011 - 🏠 Its numerical neighbours: 21722 (Clear Spring, MD, 54 mi away) and 21727 (Emmitsburg, MD, 30 mi away).
- 🔄 Backwards, 21723 becomes 32712 — and that is a real ZIP code: Apopka, FL, 776 miles away.
- 👥 31 other ZIP codes are made of exactly the same digits (12237, 12723, 12732, 17223, 17232, 17322, …). The farthest-flung twin is 73122 in Oklahoma City, OK, 1,158 miles away.
- 🧭 Farther north than 51% of all ZIP codes, and farther east than 82%.
- 🎯1,147 miles east of the geographic center of the Lower 48, near Lebanon, Kansas.
- 🌏 Dig straight through the Earth from 21723 and you would come out at 39.33°S, 103.00°E — 883 miles from Perth, Australia, the nearest big city to that spot.
- ☀Longest day of the year: 14h 57m of daylight. Shortest: 9h 24m.
- 📏 At 3.6 square miles of land, 21723 is bigger than 16% of ZIP codes — room for about 2.7 Central Parks.
- Working out the sun…
- Checking the USGS…
Source: USGS.
People and housing
| Population | 669This ZIP669 |
|---|---|
| Households | 232This ZIP232 |
| Housing units | 232This ZIP232 |
| Median age | 48.3This ZIP48.3Maryland39.4US 38.9 |
| Median household income | $241,250This ZIP$241,250Maryland$103,678US $80,734 |
| Median home value | $1,005,500This ZIP$1,005,500Maryland$419,900US $332,700 |
| Bachelor's degree or higher | 82.3%This ZIP82.3% |
| Mean commute | 36.9 minThis ZIP36.9 min |
| Population density | 185.5 / sq miThis ZIP185.5 / sq mi |
Business and tax activity
| Business establishments | 22This ZIP22 |
|---|---|
| Employees | 145This ZIP145 |
| Annual payroll | $4,941,000This ZIP$4,941,000 |
| Tax returns filed | 440This ZIP440 |
| Total adjusted gross income | $109,910,000This ZIP$109,910,000 |
Land area
| Land area | 3.61 sq miThis ZIP3.61 sq mi |
|---|---|
| Water area | 0.03 sq miThis ZIP0.03 sq mi |
ZIP codes near 21723
| ZIP | City | Distance |
|---|---|---|
21794 | West Friendship, MD | 2.9 mi |
21797 | Woodbine, MD | 3.5 mi |
21738 | Glenwood, MD | 3.6 mi |
21765 | Lisbon, MD | 3.8 mi |
21104 | Marriottsville, MD | 5.0 mi |
21784 | Sykesville, MD | 5.2 mi |
21737 | Glenelg, MD | 5.7 mi |
21036 | Dayton, MD | 6.5 mi |
21042 | Ellicott City, MD | 6.8 mi |
21041 | Ellicott City, MD | 7.2 mi |
Find every ZIP code within 10 miles of 21723 →
Questions about this ZIP code
Where is ZIP code 21723?
21723 is in Cooksville, Maryland, in Howard County, part of the Baltimore-Columbia-Towson, MD metropolitan area. Its published point location is 39.3291, -77.0026.
What county is 21723 in?
21723 lies in Howard County.
What area code is 21723?
Cooksville uses area codes 443, 667 and 410, from NANPA's telephone records.
What time zone is 21723 in?
21723 uses America/New_York.
How many people live in 21723?
About 669 people live in ZIP code 21723, in 232 households, at 185.5 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 21723?
$241,250 a year, against $103,678 across Maryland.
What ZIP codes are near 21723?
The closest are 21794 (2.9 mi), 21797 (3.5 mi), 21738 (3.6 mi), 21765 (3.8 mi) and 21104 (5 mi).
Is 21723 a PO Box ZIP code?
21723 is a standard ZIP code. A normal ZIP code with street delivery.
Download or cite
Cite this page
zipcodes.pro. “21723 ZIP Code — Cooksville, Maryland (Howard County).” Data release 2026-10-12. Retrieved 2026-10-20. https://zipcodes.pro/zip/21723
Machine-readable version of these facts:
curl https://zipcodes.pro/zip/21723.jsonUnderlying data is public domain or openly licensed — sources, vintages and licences.