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US ZIP Code Profile

ZIP Code 20818
Cabin John, Maryland

ZIP code 20818 is in Cabin John, located in Montgomery County, Maryland, within the Washington-Arlington-Alexandria metro area. Its 2020 Census population was 1,832. The estimated median adjusted gross income per tax return is $155,556, and about 41% of filers report $200,000 or more.

2020 Population
1,832
Census ZCTA
County
Montgomery
FIPS 24031
Median income (est.)
$155,556
IRS SOI 2022
Land Area
1.034 mi²
+ 0.419 mi² water

01Location & Geography

Authoritative geographic identifiers from the U.S. Census Bureau, ANSI, and FIPS standards.

Primary CityCabin John, MD
CountyMontgomery County (FIPS 24031)
StateMaryland (FIPS 24)
Metro Area (MSA)Washington-Arlington-Alexandria, DC-VA-MD-WV Metro Area (47900)
Census Region / DivisionSouth Region · South Atlantic Division
Coordinates38.973488, -77.16239
Land / Water Area1.034 mi² land · 0.419 mi² water

02Income & Economics

Distribution of the 880 individual tax returns filed in 20818 by adjusted gross income bracket (IRS SOI, 2022).

< $25K
15.9%
$25K–$50K
8.0%
$50K–$75K
8.0%
$75K–$100K
6.8%
$100K–$200K
20.4%
$200K+
40.9%
The $200,000+ bracket accounts for 85% of 20818's total adjusted gross income, from 41% of returns — a concentration that drives the gap between the median ($155,556) and the average.
Estimated median = median adjusted gross income per tax return, interpolated from IRS SOI brackets. Differs from U.S. Census household income.

03Income Over Time

Year-over-year change in 20818's IRS income metrics, 2020–2022.

Median income (2021→2022)
$155,556
▼ 3.8%
Filers earning $200K+
40.9%
▼ 1.4 pt
Total filers
880
▲ 3.5%
GET /zipc/v2/zipcodes/20818/soi?year=… $147K 2020 $162K 2021 $156K 2022
Median = adjusted gross income per return, interpolated from IRS SOI brackets. Figures are nominal (not inflation-adjusted).

04Population Trend

Decennial U.S. Census population for the 20818 ZCTA.

2000
1,987
 
2010
1,962
▼ -1.3%
2020
1,832
▼ -6.6%

05Nearby ZIP Codes — Live Radius Search

Drag the slider to filter ZIP codes by distance from 20818. Powered by the same radius endpoint developers call from the API.

GET /zipc/v2/radius

ZIP codes within range of 20818

Cabin John and its immediate neighbors, sorted by distance.

3 mi
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Distance from 20818 to any ZIP

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06USPS Postal Details

Delivery and facility attributes from the monthly USPS dataset.

ZIP ClassificationNon-Unique Zip
Facility TypePost Office
Carrier Route SortC
USPS Finance Number231350
City AliasesCabin John

07Frequently Asked Questions

What county is ZIP code 20818 in?

ZIP code 20818 is in Montgomery County, Maryland (county FIPS code 24031).

What city is ZIP code 20818?

The primary USPS city for 20818 is Cabin John, MD.

What metro area (MSA) is 20818 in?

20818 is part of the Washington-Arlington-Alexandria, DC-VA-MD-WV Metro Area (MSA code 47900).

What is the population of ZIP code 20818?

The 2020 Census population of 20818 was 1,832 residents.

What is the median income in ZIP code 20818?

Based on IRS Statistics of Income data, the estimated median adjusted gross income per tax return in 20818 is about $155,556, with around 41% of filers reporting $200,000 or more. Note that adjusted gross income is a tax measure and differs from U.S. Census household income.