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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/15621

15621

ZIP 15621 is Calumet, Pennsylvania, in Westmoreland County; area codes 724 and 878; Eastern time.

Type
No street area
Time zone
America/New_York
County
Westmoreland
Metro area
Pittsburgh, PA
Coordinates
40.2109, -79.4853

The Census map gives this ZIP code no delivery area of its own, which usually means it serves post office boxes, a single organization or a post office rather than streets of homes.

This ZIP code has no Census tabulation area of its own. Its point falls inside ZCTA 15666, whose figures describe that area — not this ZIP code.

☼ Live from 15621 — Calumet, PA

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Where 15621 is

This ZIP code has no Census tabulation area, so there is no boundary to draw — the marker is its published point location.

★ Weird and wonderful facts about 15621
  • 🔢 Type 15621 into a pocket calculator and turn it upside down: IZgSI — not quite a word, sorry.
  • ➕ As a number, 15,621 = 3 × 41 × 127. Its digits add up to 15, a total 1,657 other ZIP codes share.
  • 💾In binary, the way a computer stores it: 11110100000101
  • 🏠 Its numerical neighbours: 15620 (Bradenville, PA, 11 mi away) and 15622 (Champion, PA, 15 mi away).
  • 🔄 Backwards, 15621 becomes 12651, which is not a ZIP code at all.
  • 👥 23 other ZIP codes are made of exactly the same digits (11256, 12156, 12165, 12516, 12561, 15126, …). The farthest-flung twin is 56211 in Beardsley, MN, 944 miles away.
  • 🧭 Farther north than 58% of all ZIP codes, and farther east than 75%.
  • 🎯1,009 miles east of the geographic center of the Lower 48, near Lebanon, Kansas.
  • 🌏 Dig straight through the Earth from 15621 and you would come out at 40.21°S, 100.51°E — 1,027 miles from Perth, Australia, the nearest big city to that spot.
  • ☀Longest day of the year: 15h 02m of daylight. Shortest: 9h 18m.
🌙 The sky over 15621 today
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Source: USGS.

Land area

ZIP codes near 15621

ZIPCityDistance
15674 Norvelt, PA 0.6 mi
15689 United, PA 1.0 mi
15676 Pleasant Unity, PA 2.6 mi
15666 Mount Pleasant, PA 3.7 mi
15616 Armbrust, PA 3.8 mi
15693 Whitney, PA 5.0 mi
15697 Youngwood, PA 5.4 mi
15639 Hunker, PA 5.7 mi
15638 Hostetter, PA 5.8 mi
15688 Tarrs, PA 5.9 mi

Find every ZIP code within 10 miles of 15621 →

Questions about this ZIP code

Where is ZIP code 15621?

15621 is in Calumet, Pennsylvania, in Westmoreland County, part of the Pittsburgh, PA metropolitan area. Its published point location is 40.2109, -79.4853.

What county is 15621 in?

15621 lies in Westmoreland County.

What area code is 15621?

Calumet uses area codes 724 and 878, from NANPA's telephone records.

What time zone is 15621 in?

15621 uses America/New_York.

What ZIP codes are near 15621?

The closest are 15674 (0.6 mi), 15689 (1 mi), 15676 (2.6 mi), 15666 (3.7 mi) and 15616 (3.8 mi).

Is 15621 a PO Box ZIP code?

Possibly. The Census map gives this ZIP code no delivery area of its own, which usually means it serves post office boxes, a single organization or a post office rather than streets of homes.

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Cite this page

zipcodes.pro. “15621 ZIP Code — Calumet, Pennsylvania (Westmoreland County).” Data release 2026-10-12. Retrieved 2026-10-20. https://zipcodes.pro/zip/15621

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