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zipcodes.pro — ZIP/21778

21778

ZIP 21778 is Rocky Ridge, Maryland, in Frederick County; area codes 240, 227 and 301; Eastern time.

Type
Standard
Time zone
America/New_York
County
Frederick
Population
745
Coordinates
39.6158, -77.3284
☼ Live from 21778 — Rocky Ridge, MD

Weather right now

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Local time: —

Where 21778 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 21778
  • 🔢 Type 21778 into a pocket calculator and turn it upside down: BLLIZ — not quite a word, sorry.
  • ➕ As a number, 21,778 = 2 × 10889. Its digits add up to 25, a total 2,242 other ZIP codes share.
  • 💾In binary, the way a computer stores it: 101010100010010
  • 🏠 Its numerical neighbours: 21777 (Point Of Rocks, MD, 26 mi away) and 21779 (Rohrersville, MD, 22 mi away).
  • 🔄 Backwards, 21778 becomes 87712 — and that is a real ZIP code: Buena Vista, NM, 1,536 miles away.
  • 👥 20 other ZIP codes are made of exactly the same digits (12778, 12787, 17728, 17827, 17872, 21787, …). The farthest-flung twin is 87712 in Buena Vista, NM, 1,536 miles away.
  • 🧭 Farther north than 53% 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 21778 and you would come out at 39.62°S, 102.67°E — 908 miles from Perth, Australia, the nearest big city to that spot.
  • ☀Longest day of the year: 14h 58m of daylight. Shortest: 9h 22m.
  • 📏 At 18.2 square miles of land, 21778 is bigger than 36% of ZIP codes — room for about 14 Central Parks.
🌙 The sky over 21778 today
  • Working out the sun…
🌋 Shake report
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Source: USGS.

People and housing

Population745This ZIP745
Households332This ZIP332
Housing units332This ZIP332
Median age58.4This ZIP58.4Maryland39.4US 38.9
Median household income$76,458This ZIP$76,458Maryland$103,678US $80,734
Median home value$382,100This ZIP$382,100Maryland$419,900US $332,700
Bachelor's degree or higher27.0%This ZIP27.0%
Mean commute26.0 minThis ZIP26.0 min
Population density40.8 / sq miThis ZIP40.8 / sq mi

Business and tax activity

Business establishments16This ZIP16
Employees125This ZIP125
Annual payroll$5,506,000This ZIP$5,506,000
Tax returns filed550This ZIP550
Total adjusted gross income$41,707,000This ZIP$41,707,000

Land area

Land area18.24 sq miThis ZIP18.24 sq mi
Water area0.37 sq miThis ZIP0.37 sq mi

ZIP codes near 21778

ZIPCityDistance
21759 Ladiesburg, MD 3.8 mi
21775 New Midway, MD 4.0 mi
21757 Keymar, MD 4.0 mi
21788 Thurmont, MD 4.9 mi
21727 Emmitsburg, MD 5.0 mi
21798 Woodsboro, MD 5.7 mi
21780 Sabillasville, MD 8.6 mi
21793 Walkersville, MD 8.8 mi
21787 Taneytown, MD 9.3 mi
21791 Union Bridge, MD 9.4 mi

Find every ZIP code within 10 miles of 21778 →

Questions about this ZIP code

Where is ZIP code 21778?

21778 is in Rocky Ridge, Maryland, in Frederick County, part of the Washington-Arlington-Alexandria, DC-VA-MD-WV metropolitan area. Its published point location is 39.6158, -77.3284.

What county is 21778 in?

21778 lies in Frederick County.

What area code is 21778?

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

What time zone is 21778 in?

21778 uses America/New_York.

How many people live in 21778?

About 745 people live in ZIP code 21778, in 332 households, at 40.8 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 21778?

$76,458 a year, against $103,678 across Maryland.

What ZIP codes are near 21778?

The closest are 21759 (3.8 mi), 21775 (4 mi), 21757 (4 mi), 21788 (4.9 mi) and 21727 (5 mi).

Is 21778 a PO Box ZIP code?

21778 is a standard ZIP code. A normal ZIP code with street delivery.

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Cite this page

zipcodes.pro. “21778 ZIP Code — Rocky Ridge, Maryland (Frederick County).” Data release 2026-10-12. Retrieved 2026-10-20. https://zipcodes.pro/zip/21778

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