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zipcodes.pro — ZIP/21770

21770

ZIP 21770 is Monrovia, Maryland, in Frederick County; area codes 240 and 301; Eastern time.

Type
Standard
Time zone
America/New_York
County
Frederick
Population
8,751
Coordinates
39.3502, -77.2562
☼ Live from 21770 — Monrovia, MD

Weather right now

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Local time: —

Where 21770 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 21770
  • 🔢 Type 21770 into a pocket calculator and turn it upside down: OLLIZ — not quite a word, sorry.
  • ➕ As a number, 21,770 = 2 × 5 × 7 × 311. Its digits add up to 17, a total 2,133 other ZIP codes share.
  • 💾In binary, the way a computer stores it: 101010100001010
  • 🏠 Its numerical neighbours: 21769 (Middletown, MD, 18 mi away) and 21771 (Mount Airy, MD, 6 mi away).
  • 🔄 Backwards, 21770 becomes 07712 — and that is a real ZIP code: Asbury Park, NJ, 181 miles away.
  • 👥 37 other ZIP codes are made of exactly the same digits (01772, 02717, 02771, 07712, 07721, 10277, …). The farthest-flung twin is 77021 in Houston, TX, 1,224 miles away.
  • 🧭 Farther north than 51% of all ZIP codes, and farther east than 80%.
  • 🎯1,133 miles east of the geographic center of the Lower 48, near Lebanon, Kansas.
  • 🌏 Dig straight through the Earth from 21770 and you would come out at 39.35°S, 102.74°E — 895 miles from Perth, Australia, the nearest big city to that spot.
  • ☀Longest day of the year: 14h 57m of daylight. Shortest: 9h 23m.
  • 📏 At 11.5 square miles of land, 21770 is bigger than 29% of ZIP codes — room for about 8.7 Central Parks.
🌙 The sky over 21770 today
  • Working out the sun…
🌋 Shake report
  • Checking the USGS…

Source: USGS.

People and housing

Population8,751This ZIP8,751
Households2,622This ZIP2,622
Housing units2,632This ZIP2,632
Median age39.8This ZIP39.8Maryland39.4US 38.9
Median household income$183,571This ZIP$183,571Maryland$103,678US $80,734
Median home value$632,500This ZIP$632,500Maryland$419,900US $332,700
Bachelor's degree or higher54.8%This ZIP54.8%
Mean commute35.2 minThis ZIP35.2 min
Population density764.3 / sq miThis ZIP764.3 / sq mi

Business and tax activity

Business establishments150This ZIP150
Employees1,461This ZIP1,461
Annual payroll$82,141,000This ZIP$82,141,000
Tax returns filed4,120This ZIP4,120
Total adjusted gross income$543,817,000This ZIP$543,817,000

Land area

Land area11.45 sq miThis ZIP11.45 sq mi
Water area0.01 sq miThis ZIP0.01 sq mi

Other place names in 21770

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

ZIP codes near 21770

ZIPCityDistance
21754 Ijamsville, MD 3.4 mi
21774 New Market, MD 4.3 mi
20872 Damascus, MD 4.4 mi
21771 Mount Airy, MD 6.1 mi
21704 Frederick, MD 6.4 mi
20871 Clarksburg, MD 6.5 mi
21701 Frederick, MD 7.6 mi
21762 Libertytown, MD 9.0 mi
21705 Frederick, MD 9.2 mi
21717 Buckeystown, MD 9.4 mi

Find every ZIP code within 10 miles of 21770 →

Questions about this ZIP code

Where is ZIP code 21770?

21770 is in Monrovia, Maryland, in Frederick County, part of the Washington-Arlington-Alexandria, DC-VA-MD-WV metropolitan area. Its published point location is 39.3502, -77.2562.

What county is 21770 in?

21770 lies in Frederick County.

What area code is 21770?

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

What time zone is 21770 in?

21770 uses America/New_York.

How many people live in 21770?

About 8,751 people live in ZIP code 21770, in 2,622 households, at 764.3 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 21770?

$183,571 a year, against $103,678 across Maryland.

What ZIP codes are near 21770?

The closest are 21754 (3.4 mi), 21774 (4.3 mi), 20872 (4.4 mi), 21771 (6.1 mi) and 21704 (6.4 mi).

Is 21770 a PO Box ZIP code?

21770 is a standard ZIP code. A normal ZIP code with street delivery.

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zipcodes.pro. “21770 ZIP Code — Monrovia, Maryland (Frederick County).” Data release 2026-10-12. Retrieved 2026-10-20. https://zipcodes.pro/zip/21770

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