What city is 20879 in?

20879 is a Gaithersburg, MD mailing address. By land area, 22% lies inside Flower Hill, 11% lies inside Gaithersburg, 4% lies inside Germantown and 1% lies inside Montgomery Village; the rest is outside any Census-defined city or community.

What is the population of 20879?

About 25,264 people (±1,909), according to the Census Bureau's American Community Survey 5-year estimates for 2020–2024. The 2020 Census counted 26,176.

What is the median household income in 20879?

$112,104 (±$8,413), compared with $103,678 for Maryland as a whole. Half the households in the ZIP code earn more and half earn less.

How many carrier routes and mailboxes are in 20879?

18 USPS carrier routes with 9,103 residential and 1,220 business mailboxes (10,323 in all), from the route data stored by EDDM2GO. An EDDM mailing can target any combination of these routes.

What ZIP codes are near 20879?

The closest, measured center to center: 20880 (1.9 mi, Washington Grove), 20877 (2.4 mi, Gaithersburg), 20886 (2.6 mi, Montgomery Village), 20855 (2.7 mi, Redland), 20899 (3.2 mi, Gaithersburg) and 20882 (4.2 mi, Damascus).

20879 ZIP Code, Gaithersburg, MD

20879 is a ZIP code in Gaithersburg, Maryland in Montgomery County. It covers 8.6 square miles of land. The closest ZIP codes are 20880, 20877 and 20886. 25,264 people live here in 8,651 households. At about 2,932 people per square mile it has suburban density, and owners and renters are mixed (70% own). Median household income is $112,104, close to the Maryland median of $103,678.

Quick facts

Mailing city: Gaithersburg, MD
County: Montgomery County
Land area: 8.6 sq mi
Population: 25,264
Median household income: $112,104
Carrier routes: 18 (9,103 homes)

Key figures

Measure	Value
Residents	25,264
Households	8,651
Median household income	$112,104
Income per person	$48,025
Median age	36.4
Homeowners	69.8%
Median home value	$468,100
Median rent	$1,942
Bachelor's degree or higher	44.8%
Average commute (minutes)	31.3
Households with kids under 18	30.7%
Moved in the past year	9.3%
Below the poverty line	7.5%
Broadband internet	97.6%
Speak a non-English language at home	49.4%

Household income

% of households	Value
<$10K	3.4%
$10–15K	1.8%
$15–25K	3.2%
$25–35K	2.8%
$35–50K	6.3%
$50–75K	13.9%
$75–100K	12.5%
$100–150K	22.4%
$150–200K	12.1%
$200K+	21.6%

Age

% of all residents	Value
<10	13.1%
10–19	12.6%
20–24	5.9%
25–34	16.0%
35–44	12.6%
45–54	11.9%
55–64	12.9%
65–74	10.4%
75+	4.6%

Tenure

% of housing units	Value
Owned, with mortgage	50.1%
Owned outright	18.6%
Rented	29.4%
Vacant	1.9%

Type of building

% of housing units	Value
Detached house	39.9%
Townhome	31.9%
2–4 units	1.6%
5–19 units	18.3%
20+ units	7.5%
Mobile / other	0.7%

Businesses in 20879

961 business establishments with 16,628 employees (ZIP Codes Business Patterns 2023).

Construction: 164
Professional, Scientific, and Technical Services: 128
Other Services (except Public Administration): 112
Health Care and Social Assistance: 84
Retail Trade: 81
Accommodation and Food Services: 73
Administrative and Support and Waste Management and Remediation Services: 65
Wholesale Trade: 61

EDDM carrier routes

20879 has 18 USPS carrier routes with 9,103 residential and 1,220 business mailboxes. Open the EDDM route map.

Carrier routes in 20879

20879 has 18 USPS carrier routes (15 city (C), 3 rural (R)) with 9,103 residential and 1,220 business mailboxes. Routes range from 125 homes (R042) to 726 homes (C059); the median route has 530 homes. The Census counted 8,651 households in 20879 (2020–2024 average); USPS counts current mailboxes, including new and vacant homes.

Homes per route	Routes
1–249	2
250–499	5
500–749	11
750–999	0
1,000–1,499	0
1,500+	0

Best routes in 20879 for…

Most businesses

For B2B offers: office supplies, cleaning, IT, catering and commercial services.

Route C028 — USPS business mailboxes 240, 212 homes
Route C020 — USPS business mailboxes 212, 303 homes
Route C060 — USPS business mailboxes 157, 474 homes
Route C055 — USPS business mailboxes 141, 473 homes
Route C064 — USPS business mailboxes 138, 407 homes

Select these 5 routes on the route map

Every carrier route in 20879

Route	Type	Homes	Businesses	Est. median income	Est. owners	Est. families with kids	Est. moved in past year
C009	City	619	2	$115,814	—	—	—
C012	City	636	121	—	—	—	—
C016	City	591	0	$115,814	—	—	—
C020	City	303	212	$112,551	—	—	—
C022	City	476	1	$101,290	—	—	—
C024	City	504	28	$90,298	—	—	—
C026	City	522	82	—	—	—	—
C028	City	212	240	$90,808	—	—	—
C052	City	585	0	$82,057	—	—	—
C053	City	723	17	$82,057	—	—	—
C055	City	473	141	$115,814	—	—	—
C058	City	647	28	$40,420	—	—	—
C059	City	726	47	$168,053	—	—	—
C060	City	474	157	$101,290	—	—	—
C064	City	407	138	$82,057	—	—	—
R036	Rural	537	3	$112,551	—	—	—
R042	Rural	125	0	$187,817	—	—	—
R056	Rural	543	3	$200,001+	—	—	—

Income, owners, families and movers are estimates for each route (how we estimate them); mailbox counts are current USPS figures. Open 20879 on the EDDM route map.

How route demographics are estimated

Mailbox counts come from USPS; demographics are estimates

The number of homes and businesses on each carrier route is the current USPS EDDM count. The Census Bureau does not publish figures for carrier routes, so income, homeownership, ages, families, movers and housing age on a route are EDDM2GO estimates built from Census block groups (neighborhood areas of roughly 600 to 3,000 people).

How a route gets its figures: the block-group length-share method

We trace each route's streets every 25 meters and record which block group each stretch falls in. The route's homes are spread along its streets in proportion to length, so a route with 60% of its street length in one block group is assumed to have 60% of its homes there. Each block group then contributes its Census counts in proportion to the share of its housing units that sit on the route (capped at the whole block group). Medians are recalculated from the combined income, home-value and age brackets, the way the Census Bureau computes them, not averaged.

Margins of error

Census survey figures carry a margin of error at 90% confidence; we carry it through the calculation and show it as ±. Our margins treat the route-to-block-group split as exact, so the real uncertainty is larger. Routes with fewer than 100 estimated households, large margins, or streets we could not place are flagged.

Different years

USPS mailbox counts are current. Census figures are 5-year averages for 2020–2024, so a new subdivision may have more homes on the route today than the Census counted. Use the route figures to compare routes with each other, not as an exact head count.

Why some routes show identical figures

Two routes that run through the same block group get the same percentages and medians, because the Census publishes one set of figures for the whole block group. Their mailbox counts still differ, and those are exact.

Route and mailbox counts: USPS EDDM route data. Route demographics: EDDM2GO estimates from U.S. Census Bureau American Community Survey 5-year block-group data (2020–2024) and 2024 cartographic block-group boundaries. This product uses the Census Bureau Data API but is not endorsed or certified by the Census Bureau.

Nearby ZIP codes

20880 — Washington Grove town, MD (1.9 mi)
20877 — Gaithersburg city, MD (2.4 mi)
20886 — Montgomery Village CDP, MD (2.6 mi)
20855 — Redland CDP, MD (2.7 mi)
20899 — Gaithersburg city, MD (3.2 mi)
20882 — Damascus CDP, MD (4.2 mi)
20876 — Germantown CDP, MD (4.6 mi)
20832 — Olney CDP, MD (4.7 mi)

Areas that include 20879

Gaithersburg, MD ZIP codes — 5 ZIP codes
Flower Hill, MD ZIP codes — 1 ZIP code
Montgomery County ZIP codes — 48 ZIP codes
Maryland ZIP code data

Where it ranks

No. 3 of 37: lowest median age in Montgomery County

Mail every home in 20879

Route counts on this page price as Full Service 6.5 × 9 postcards: we print, bundle by carrier route and hand the mailing to USPS. Prefer to take it to the Post Office yourself? Print only costs less and you pay postage at drop-off.

EDDM guides

ZIP code statistics describe the Census ZIP Code Tabulation Area (ZCTA) 20879, which approximates the USPS ZIP code area. Census figures: American Community Survey 5-year estimates, 2020–2024.

Frequently asked questions

What city is 20879 in?: 20879 is a Gaithersburg, MD mailing address. By land area, 22% lies inside Flower Hill, 11% lies inside Gaithersburg, 4% lies inside Germantown and 1% lies inside Montgomery Village; the rest is outside any Census-defined city or community.
What county is 20879 in?: 20879 is in Montgomery County.
What is the population of 20879?: About 25,264 people (±1,909), according to the Census Bureau's American Community Survey 5-year estimates for 2020–2024. The 2020 Census counted 26,176.
What is the median household income in 20879?: $112,104 (±$8,413), compared with $103,678 for Maryland as a whole. Half the households in the ZIP code earn more and half earn less.
How many carrier routes and mailboxes are in 20879?: 18 USPS carrier routes with 9,103 residential and 1,220 business mailboxes (10,323 in all), from the route data stored by EDDM2GO. An EDDM mailing can target any combination of these routes.
What ZIP codes are near 20879?: The closest, measured center to center: 20880 (1.9 mi, Washington Grove), 20877 (2.4 mi, Gaithersburg), 20886 (2.6 mi, Montgomery Village), 20855 (2.7 mi, Redland), 20899 (3.2 mi, Gaithersburg) and 20882 (4.2 mi, Damascus).

This product uses the Census Bureau Data API but is not endorsed or certified by the Census Bureau.