Residential delivery area · Maryland
ZIP Code 20878: Gaithersburg, MD
ZIP code 20878 uses the postal name Gaithersburg, Maryland and lies entirely in Montgomery County (Census 2020 ZIP-county file). About 66,000 people live there (Census Bureau, ACS 2020-2024), the most populous of Gaithersburg's 5 residential ZIP codes. Median household income is $144,313 (Census Bureau, ACS 2020-2024). By Census place, its land lies in Gaithersburg (27%), North Potomac (25%), Darnestown (23%) and Travilah (7%); 17% is outside any Census place.
- ACS2020-24
- Census2020
- FHFA2025
- ZBP2023
- IRS2022
- Town
- Gaithersburg · 5 residential ZIPs
- County
- Montgomery County
- Census places
- Gaithersburg (27%); North Potomac (25%) census-designated place; Darnestown (23%) census-designated place; Travilah (7%) census-designated place
- Neighborhoods
- Bennington, Bridlewood, Coventry, Diamond Farms, Dorsey Estates, Fernshire Farms and 3 more GeoNames
- Metro area
- Washington-Arlington-Alexandria, DC-VA-MD-WV
- House districts
- MD-8 (50%), MD-6 (50%) 119th Congress, by share of land
- State
- Maryland
- Time zone
- Eastern
- Land area
- 20.4 sq mi · 3,233 people per sq mi
Where is ZIP code 20878?
20878 centers on 39.113°, -77.250° and covers 20.4 square miles of land plus 0.4 of water. It borders 6 ZIP codes: 20899, 20874, 20877, 20850, 20854, 20879.
The map draws ZIP code areas only. For the streets inside 20878, open its center on OpenStreetMap.
Source: U.S. Census Bureau, 2020 ZCTA cartographic boundaries and the 2023 Gazetteer (2020 ZCTAs); ZIP-to-county shares, Census places and House districts (119th Congress) from the Census 2020 relationship files (shares of land); metro area from the OMB delineation (July 2023); town name and time zone from simplemaps US ZIP Codes (CC BY 4.0); neighborhoods from the GeoNames gazetteer (CC BY 4.0), placed in this ZIP code by PlainZIP.
How does 20878 compare with the rest of Gaithersburg?
| Measure | 20878 | In Gaithersburg | In Montgomery County | In MD |
|---|---|---|---|---|
| People (ACS 2020-2024) | 66,115 | 1st of 5 | 2nd of 53 | 3rd of 477 |
| Median household income | $144k | 2nd of 4 | 22nd of 41 | 63rd of 293 |
| Median home value | $716k | 2nd of 4 | 17th of 41 | 26th of 320 |
Its median household income is higher than in 95% of U.S. residential ZIP codes, and it is denser than 89% of all U.S. residential ZIP codes. ZIP codes at the ACS caps ($250,000 or more for household income, $2,000,000 or more for home value) share the top rank.
Source: U.S. Census Bureau, ACS 2020-2024 5-year estimates (B01003, B19013, B25077); ranks by PlainZIP over residential ZIP codes (ZCTAs).
How many people live in 20878?
The 2020 Census counted 65,990 people in 20878; the ACS, which samples households over 2020-2024, estimates 66,115. Between the 2010 and 2020 censuses its population grew 5.7% (its boundary stayed at least 90% the same).
- People, ACS 2020-2024
- 66,115
- 2020 Census count
- 65,990+5.7% since 2010 (62,446)
- Households
- 24,237
- Median age
- 41.4
Source: U.S. Census Bureau, ACS 2020-2024 5-year estimates (B01003, B01002, B11001); 2020 Census (DHC P1); 2010 Census (SF1 P1).
Who lives in 20878?
Of the 66,115 people the ACS estimates in 20878, 22.0% are under 18 and 16.0% are 65 or older. The largest group by race and Hispanic origin is White (not Hispanic) (43.5%), then Asian (not Hispanic) (27.3%).
- Under 1822.0%
- 18 to 6462.0%
- 65 and older16.0%
- White, not Hispanic43.5%
- Asian, not Hispanic27.3%
- Hispanic or Latino14.2%
- Black, not Hispanic10.2%
- Other or two or more4.8%
Source: U.S. Census Bureau, ACS 2020-2024 5-year estimates (B01001 age by sex, B03002 Hispanic or Latino origin by race); shares of the estimated population, small ZIP codes carry wide margins.
What do households in 20878 earn?
Median household income is $144,313 (ACS 2020-2024), the 22nd highest of the 41 ranked ZIP codes in Montgomery County. It fell from $163,088 in 2015-2019 (in 2024 dollars), a change larger than the surveys' margins of error.
- Median household income
- $144,313
- Income per person
- $69,431
- Below the poverty line
- 5.2%
- Unemployed (of the labor force)
- 4.0%
- Adults 25+ with a bachelor's degree
- 70.3%
- Adjusted gross income per tax return, 2022
- $136,95233,280 returns; wages 73% of AGI (IRS)
Source: U.S. Census Bureau, ACS 2020-2024 and 2015-2019 5-year estimates (B19013, B19301, B17001, B23025, B15003; 2015-2019 dollars converted with the BLS CPI-U, 1.22699); IRS Statistics of Income, ZIP code data, tax year 2022 (adjusted gross income per return, filed under the address on the return).
What are homes worth in 20878?
FHFA's house price index for 20878, built from repeat sales and appraisals of the same homes, rose 54% from 2015 to 2025 and rose 41% from 2020 to 2025, and moved +3.4% in 2025.
- Median home value (owners' estimate)
- $715,800
- Median gross rent
- $2,226
- Homes owned by their occupants
- 69.2%
- Housing units
- 25,127
Source: U.S. Census Bureau, ACS 2020-2024 5-year estimates (B25077, B25064, B25003, B25001); FHFA House Price Index, annual five-digit ZIP, updated 2026-03-31.
What businesses are in 20878?
2,087 business establishments had a location in this ZIP code in 2023, 129 more than in 2018; the most are in professional, scientific, and technical services (ZIP Code Business Patterns).
- Professional, scientific, and technical services515
- Management of companies and enterprises332
- Administrative and support and waste management and remediation services214
- Health care and social assistance164
- Accommodation and food services159
- Retail trade132
Source: U.S. Census Bureau, ZIP Code Business Patterns 2023 and 2018 (establishments with paid employees, by the business's ZIP code).
Which ZIP codes are next to 20878?
| ZIP | Town | People | Household income | Distance |
|---|---|---|---|---|
| 20899 | Gaithersburg | 57 | $24k | 2.9 mi |
| 20874 | Germantown | 62,738 | $115k | 3.1 mi |
| 20877 | Gaithersburg | 38,546 | $93k | 3.7 mi |
| 20850 | Rockville | 50,353 | $126k | 4.1 mi |
| 20854 | Potomac | 50,498 | $250k+ | 5.7 mi |
| 20879 | Gaithersburg | 25,264 | $112k | 6.0 mi |
| 20880 | Washington Grove | 577 | $135k | 4.5 mi (near) |
| 20886 | Montgomery Village | 34,718 | $99k | 5.8 mi (near) |
Source: PlainZIP from the Census 2020 ZCTA boundaries (shared edges) and internal points; figures ACS 2020-2024.