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.
ZIP Codes With the Lowest Average Income in Maryland
What this measures. Total adjusted gross income divided by tax returns filed, lowest first. ZIP codes with fewer than 200 returns are excluded: the IRS suppresses small cells and the remainder swing too wildly to rank. Source: IRS Statistics of Income, ZIP code data, data release 2026-10-12.
Showing the top 50 of 385 ZIP codes in Maryland that
have this figure
and meet the threshold above.
21223 ranks 1st at $33,838, against $58,157 in
50th place.