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 — CITY/MD/RIDERWOOD

Riderwood ZIP code, Maryland

The ZIP code for Riderwood, MD is 21139, and its area codes are 410, 443 and 667.

USPS city name
1 ZIP code
Area codes
410, 443, 667

NANPA lists no telephone rate centre for Riderwood itself, so these are the area codes of the nearest one, Towson (1.2 miles). A town on an area-code boundary can differ from its neighbour.

ZIP codes addressed as Riderwood

ZIP codes with the USPS city name Riderwood
ZIP City Type
21139 Riderwood , MD No street area

Towns near Riderwood

Towns near Riderwood
TownPopulationDistance
Lutherville 6,574 1.9 mi
Towson 58,679 1.9 mi
Mays Chapel 16,066 2.4 mi
Pikesville 33,524 3.0 mi
Timonium 10,304 3.6 mi
Hampton 5,372 4.5 mi
Cockeysville 23,962 4.8 mi
Parkville 30,549 5.5 mi
Garrison 9,469 5.5 mi
Lochearn 27,074 6.0 mi
Carney 28,343 6.7 mi
Owings Mills 37,245 7.5 mi
Overlea 13,035 7.7 mi
Milford Mill 30,829 7.7 mi

More nearby: every ZIP code in Baltimore County · Maryland ZIP codes

Cite this page

zipcodes.pro. “Riderwood, MD ZIP codes.” Data release 2026-10-12. Retrieved 2026-10-20. https://zipcodes.pro/city/md/riderwood

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