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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/01821

01821

ZIP 01821 is in Billerica, Massachusetts, in Middlesex County; area codes 978 and 508; Eastern time. Billerica has 2 ZIP codes; the other is 01822.

Type
Standard
Time zone
America/New_York
County
Middlesex
Population
30,143
Coordinates
42.5493, -71.2517
☼ Live from 01821 — Billerica, MA

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Where 01821 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 01821
  • 🔢 Type 01821 into a pocket calculator and turn it upside down: IZBIO — not quite a word, sorry.
  • ➕ As a number, 1,821 = 3 × 607. Its digits add up to 12, a total 940 other ZIP codes share.
  • 💾In binary, the way a computer stores it: 11100011101
  • 🏠 Its numerical neighbours: 01815 (Woburn, MA, 7 mi away) and 01822 (Billerica, MA, 1 mi away).
  • 🔄 Backwards, 01821 becomes 12810 — and that is a real ZIP code: Athol, NY, 153 miles away.
  • 👥 34 other ZIP codes are made of exactly the same digits (01128, 01812, 02118, 10128, 10281, 11208, …). The farthest-flung twin is 81120 in Antonito, CO, 1,884 miles away.
  • 🧭 Farther north than 79% of all ZIP codes, and farther east than 96%.
  • 🎯1,427 miles east of the geographic center of the Lower 48, near Lebanon, Kansas.
  • 🌏 Dig straight through the Earth from 01821 and you would come out at 42.55°S, 108.75°E — 829 miles from Perth, Australia, the nearest big city to that spot.
  • ☀Longest day of the year: 15h 18m of daylight. Shortest: 9h 03m.
  • 📏 At 16.6 square miles of land, 01821 is bigger than 34% of ZIP codes — room for about 13 Central Parks.
🌙 The sky over 01821 today
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🌋 Shake report
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Source: USGS.

People and housing

Population30,143This ZIP30,143
Households11,312This ZIP11,312
Housing units11,430This ZIP11,430
Median age44.3This ZIP44.3Massachusetts40.0US 38.9
Median household income$149,042This ZIP$149,042Massachusetts$103,960US $80,734
Median home value$615,100This ZIP$615,100Massachusetts$562,100US $332,700
Median gross rent$2,346This ZIP$2,346Massachusetts$1,762US $1,413
Bachelor's degree or higher40.2%This ZIP40.2%
Mean commute25.9 minThis ZIP25.9 min
Population density1,816.7 / sq miThis ZIP1,816.7 / sq mi

Business and tax activity

Business establishments717This ZIP717
Employees15,332This ZIP15,332
Annual payroll$1,548,721,000This ZIP$1,548,721,000
Tax returns filed16,920This ZIP16,920
Total adjusted gross income$1,663,097,000This ZIP$1,663,097,000

Land area

Land area16.59 sq miThis ZIP16.59 sq mi
Water area0.40 sq miThis ZIP0.40 sq mi

Other place names in 01821

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

ZIP codes near 01821

ZIPCityDistance
01822 Billerica, MA 1.1 mi
01865 Nutting Lake, MA 1.2 mi
01866 Pinehurst, MA 1.8 mi
01862 North Billerica, MA 3.0 mi
01730 Bedford, MA 3.8 mi
01803 Burlington, MA 4.1 mi
01805 Burlington, MA 4.2 mi
01876 Tewksbury, MA 4.5 mi
01887 Wilmington, MA 4.6 mi
01741 Carlisle, MA 5.6 mi

Find every ZIP code within 10 miles of 01821 →

Questions about this ZIP code

Where is ZIP code 01821?

01821 is in Billerica, Massachusetts, in Middlesex County, part of the Boston-Cambridge-Newton, MA-NH metropolitan area. Its published point location is 42.5493, -71.2517.

What county is 01821 in?

01821 lies in Middlesex County.

What area code is 01821?

Billerica uses area codes 978 and 508, from NANPA's telephone records.

What time zone is 01821 in?

01821 uses America/New_York.

How many people live in 01821?

About 30,143 people live in ZIP code 01821, in 11,312 households, at 1,816.7 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 01821?

$149,042 a year, against $103,960 across Massachusetts.

What ZIP codes are near 01821?

The closest are 01822 (1.1 mi), 01865 (1.2 mi), 01866 (1.8 mi), 01862 (3 mi) and 01730 (3.8 mi).

Is 01821 a PO Box ZIP code?

01821 is a standard ZIP code. A normal ZIP code with street delivery.

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Cite this page

zipcodes.pro. “01821 ZIP Code — Billerica, Massachusetts (Middlesex County).” Data release 2026-10-12. Retrieved 2026-10-20. https://zipcodes.pro/zip/01821

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