Every ZIP code in the United States, with weather, radar, trivia and the numbers behind it. Five digits since 1963!

ZIP stands for Zone Improvement Plan. The codes went live on July 1, 1963.The lowest ZIP code is 00501 — the IRS in Holtsville, New York.The highest ZIP code is 99950, in Ketchikan, Alaska.Type 07734 into a calculator and turn it upside down: hELLO. It is Keansburg, New Jersey.12345 belongs to one company: General Electric in Schenectady, New York.The first digit is a region: 0 is New England and New Jersey, 9 is the West Coast, Alaska and Hawaii.Mr. ZIP, the cartoon mailman, was the mascot that sold the idea to America.ZIP+4 arrived in 1983 and can narrow a ZIP down to one side of one block.A ZIP code is a mail route, not a place: plenty of them cross county and even state lines.Play ZIP Hunt: guess the secret ZIP code of the day in six tries.
zipcodes.pro — ZIP/21704

21704

ZIP 21704 is in Frederick, Maryland, in Frederick County; area codes 240, 301 and 227; Eastern time. Frederick has 6 ZIP codes; the others are 21701, 21702, 21703, 21705 and 21709.

Type
Standard
Time zone
America/New_York
County
Frederick
Population
20,006
Coordinates
39.3549, -77.3759
☼ Live from 21704 — Frederick, MD

Weather right now

Asking the National Weather Service…

NEXRAD radar
Finding the nearest radar…
Local time: —

Where 21704 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.

★ Weird and wonderful facts about 21704
  • 🔢 Type 21704 into a pocket calculator and turn it upside down: hOLIZ — not quite a word, sorry.
  • ➕ As a number, 21,704 = 2 × 2 × 2 × 2713. Its digits add up to 14, a total 1,416 other ZIP codes share.
  • 💾In binary, the way a computer stores it: 101010011001000
  • 🏠 Its numerical neighbours: 21703 (Frederick, MD, 5 mi away) and 21705 (Frederick, MD, 4 mi away).
  • 🔄 Backwards, 21704 becomes 40712, which is not a ZIP code at all.
  • 👥 66 other ZIP codes are made of exactly the same digits (01247, 01472, 01742, 02471, 02714, 02741, …). The farthest-flung twin is 74102 in Tulsa, OK, 1,039 miles away.
  • 🧭 Farther north than 51% of all ZIP codes, and farther east than 80%.
  • 🎯1,127 miles east of the geographic center of the Lower 48, near Lebanon, Kansas.
  • 🌏 Dig straight through the Earth from 21704 and you would come out at 39.35°S, 102.62°E — 901 miles from Perth, Australia, the nearest big city to that spot.
  • ☀Longest day of the year: 14h 57m of daylight. Shortest: 9h 23m.
  • 📏 At 26.6 square miles of land, 21704 is bigger than 43% of ZIP codes — room for about 20 Central Parks.
🌙 The sky over 21704 today
  • Working out the sun…
🌋 Shake report
  • Checking the USGS…

Source: USGS.

People and housing

Population20,006This ZIP20,006
Households6,136This ZIP6,136
Housing units6,257This ZIP6,257
Median age38.6This ZIP38.6Maryland39.4US 38.9
Median household income$161,063This ZIP$161,063Maryland$103,678US $80,734
Median home value$612,000This ZIP$612,000Maryland$419,900US $332,700
Median gross rent$2,536This ZIP$2,536Maryland$1,705US $1,413
Bachelor's degree or higher57.4%This ZIP57.4%
Mean commute33.5 minThis ZIP33.5 min
Population density751.2 / sq miThis ZIP751.2 / sq mi

Business and tax activity

Business establishments954This ZIP954
Employees16,206This ZIP16,206
Annual payroll$1,024,625,000This ZIP$1,024,625,000
Tax returns filed10,100This ZIP10,100
Total adjusted gross income$1,427,749,000This ZIP$1,427,749,000

Land area

Land area26.63 sq miThis ZIP26.63 sq mi
Water area0.17 sq miThis ZIP0.17 sq mi

Other place names in 21704

Census places whose land this ZIP code overlaps. The Postal Service may accept other city names in an address, too.

ZIP codes near 21704

ZIPCityDistance
21717 Buckeystown, MD 3.2 mi
21754 Ijamsville, MD 3.6 mi
21705 Frederick, MD 4.2 mi
21710 Adamstown, MD 4.4 mi
21703 Frederick, MD 5.3 mi
21770 Monrovia, MD 6.4 mi
21701 Frederick, MD 6.5 mi
21774 New Market, MD 6.6 mi
21709 Frederick, MD 8.0 mi
21714 Braddock Heights, MD 8.1 mi

Find every ZIP code within 10 miles of 21704 →

Questions about this ZIP code

Where is ZIP code 21704?

21704 is in Frederick, Maryland, in Frederick County, part of the Washington-Arlington-Alexandria, DC-VA-MD-WV metropolitan area. Its published point location is 39.3549, -77.3759.

What county is 21704 in?

21704 lies in Frederick County.

What area code is 21704?

Frederick uses area codes 240, 301 and 227, from NANPA's telephone records.

What time zone is 21704 in?

21704 uses America/New_York.

How many people live in 21704?

About 20,006 people live in ZIP code 21704, in 6,136 households, at 751.2 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 21704?

$161,063 a year, against $103,678 across Maryland.

What ZIP codes are near 21704?

The closest are 21717 (3.2 mi), 21754 (3.6 mi), 21705 (4.2 mi), 21710 (4.4 mi) and 21703 (5.3 mi).

Is 21704 a PO Box ZIP code?

21704 is a standard ZIP code. A normal ZIP code with street delivery.

Download or cite

Cite this page

zipcodes.pro. “21704 ZIP Code — Frederick, Maryland (Frederick County).” Data release 2026-10-12. Retrieved 2026-10-20. https://zipcodes.pro/zip/21704

Machine-readable version of these facts:

curl https://zipcodes.pro/zip/21704.json

Underlying data is public domain or openly licensed — sources, vintages and licences.