ZIP codes
214
Area Code 240
Explore ZIP codes in area code 240 — covering MD — 214 ZIP codes — 3,002,108 residents. Population, income, and housing at a glance.
Population
3,002,108
States
MD
Median household income (avg.)
$120,320
Average home value
$463,869
Where is area code 240?
Area code 240 maps to 214 indexable ZIP codes on US5 across MD, with a combined ZIP-area population of about 3,002,108.
Among places with the most population in this NPA on US5 are Gaithersburg, MD, Aspen Hill, MD, Frederick, MD, Bethesda, MD, and Silver Spring, MD. Open any ZIP below for full demographics, housing, and nearby services.
The most populous ZIP currently listed for 240 is 20906 (about 71,216 residents).
Income and housing in 240
Across ZIPs with income data in area code 240, the average median household income is about $120,320 — about 60% above the U.S. median ($75,149).
Average median home value across those ZIPs is about $463,869.
On this page’s income ranking, ZIP 20759 is near the top at about $250,001.
How area code 240 numbering works
In the North American Numbering Plan, the first three digits of a 10-digit phone number are the Numbering Plan Area (NPA), commonly called the area code. Digits 4–6 are the central office code (NXX / “exchange”), and the last four digits identify the individual line.
US5’s 240 page groups ZIP codes that are associated with this NPA in published geography data. That is a place-based view — it is not a live directory of every phone number assigned to 240, and overlays or split NPAs can mean multiple area codes serve the same metro.
Scams and caller ID spoofing
Seeing area code 240 on caller ID does not prove the caller is physically in MD. Spoofing tools can display almost any NPA, including local-looking numbers used in IRS, bank, warranty, and “grandparent” scams.
If you receive an unexpected call about taxes, arrests, or locked accounts: hang up, do not share codes or remote-access software, and contact the organization using a number from its official website or your statement — not a number the caller provides. US5 publishes geography for research; it does not verify live callers.
ZIP codes in area code 240
Frequently asked questions
Where is area code 240?
Area code 240 is associated with ZIP codes in MD on US5, covering about 3,002,108 combined ZIP-area residents across 214 codes. Browse the ZIP table on this page for cities and counties.
How many ZIP codes are in area code 240?
US5 currently lists 214 indexable ZIP codes for area code 240. Counts can change as geography publishes update.
What is the average income in area code 240?
The average of ZIP median household incomes in area code 240 is about $120,320 (about 60% above the U.S. median ($75,149)). Individual neighborhoods vary — sort the ZIP table by income to compare.
What is an NXX or “number block” in area code 240?
After the area code, the next three digits (NXX) identify a central office / exchange “block” of up to 10,000 numbers. US5 focuses on ZIP geography for 240; for live number assignment details, use official NANPA / carrier resources.
Does a 240 caller ID mean the person is local?
No. Caller ID can be spoofed to show area code 240 even when the caller is elsewhere. Treat unexpected calls about money, arrests, or account lockouts as suspicious and verify through official channels.
How can I avoid phone scams that use area code 240?
Do not trust caller ID alone. Never send gift cards, wire money, or install remote-access apps because a caller claims to be from the IRS, a bank, or tech support. Hang up and call back using a published number from a statement or official website.
What cities use area code 240?
Larger population clusters on US5 for 240 include Gaithersburg, MD, Aspen Hill, MD, Frederick, MD, Bethesda, MD, and Silver Spring, MD. Open linked ZIP pages for neighborhood-level demographics.