Residential delivery area · Maryland
ZIP Code 21771: Mount Airy, MD
ZIP code 21771 uses the postal name Mount Airy, Maryland and lies mostly in Frederick County (51% of its land), reaching into Carroll County, Howard County and Montgomery County (Census 2020 ZIP-county file). About 33,000 people live there (Census Bureau, ACS 2020-2024). Median household income is $157,302 (Census Bureau, ACS 2020-2024). By Census place, its land lies in Green Valley (7%) and Mount Airy (5%); 88% is outside any Census place.
- ACS2020-24
- Census2020
- FHFA2025
- ZBP2023
- IRS2022
- Town
- Mount Airy · its only residential ZIP
- County
- Frederick County (51%); Carroll County (26%); Howard County (18%); Montgomery County (4%)
- Census places
- Green Valley (7%) census-designated place; Mount Airy (5%)
- Neighborhoods
- Conestoga Heights, Merridale, Merridale Gardens, Mount Airy Village West, Poulsen Heights, Rising Ridge and 1 more GeoNames
- Metro area
- Washington-Arlington-Alexandria, DC-VA-MD-WV
- House districts
- MD-6 (55%), MD-3 (36%), MD-2 (9%) 119th Congress, by share of land
- State
- Maryland
- Time zone
- Eastern
- Land area
- 89.5 sq mi · 369 people per sq mi
Where is ZIP code 21771?
21771 centers on 39.395°, -77.158° and covers 89.5 square miles of land plus 0.2 of water. It borders 9 ZIP codes: 21770, 21774, 21797, 20872, 21776, 21791, 21701, 20882, 21157.
The map draws ZIP code areas only. For the streets inside 21771, 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 21771 compare with the rest of Frederick County?
| Measure | 21771 | In Frederick County | In MD |
|---|---|---|---|
| People (ACS 2020-2024) | 33,031 | 4th of 35 | 71st of 477 |
| Median household income | $157k | 10th of 26 | 49th of 293 |
| Median home value | $556k | 7th of 28 | 72nd of 320 |
Its median household income is higher than in 97% of U.S. residential ZIP codes, and it is denser than 69% 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 21771?
The 2020 Census counted 30,697 people in 21771; the ACS, which samples households over 2020-2024, estimates 33,031. Between the 2010 and 2020 censuses its population grew 3.8% (its boundary stayed at least 90% the same).
- People, ACS 2020-2024
- 33,031
- 2020 Census count
- 30,697+3.8% since 2010 (29,563)
- Households
- 11,226
- Median age
- 40.9
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 21771?
Of the 33,031 people the ACS estimates in 21771, 24.2% are under 18 and 15.6% are 65 or older. The largest group by race and Hispanic origin is White (not Hispanic) (83.2%).
- Under 1824.2%
- 18 to 6460.1%
- 65 and older15.6%
- White, not Hispanic83.2%
- Hispanic or Latino8.3%
- Black, not Hispanic3.6%
- Other or two or more3.5%
- Asian, not Hispanic1.4%
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 21771 earn?
Median household income is $157,302 (ACS 2020-2024), the 10th highest of the 26 ranked ZIP codes in Frederick County. It is not measurably different from 2015-2019 ($159,036 in 2024 dollars): the change is within the surveys' margins of error.
- Median household income
- $157,302
- Income per person
- $60,220
- Below the poverty line
- 3.1%
- Unemployed (of the labor force)
- 4.3%
- Adults 25+ with a bachelor's degree
- 48.8%
- Adjusted gross income per tax return, 2022
- $118,80715,440 returns; wages 74% 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 21771?
FHFA's house price index for 21771, built from repeat sales and appraisals of the same homes, rose 61% from 2015 to 2025 and rose 43% from 2020 to 2025, and moved +2.6% in 2025.
- Median home value (owners' estimate)
- $556,200
- Median gross rent
- $2,252
- Homes owned by their occupants
- 94.0%
- Housing units
- 11,758
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 21771?
759 business establishments had a location in this ZIP code in 2023, 10 more than in 2018; the most are in construction (ZIP Code Business Patterns).
- Construction182
- Professional, scientific, and technical services95
- Other services (except public administration)72
- Administrative and support and waste management and remediation services71
- Health care and social assistance71
- Retail trade70
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 21771?
| ZIP | Town | People | Household income | Distance |
|---|---|---|---|---|
| 21770 | Monrovia | 8,751 | $184k | 6.1 mi |
| 21774 | New Market | 17,134 | $171k | 6.3 mi |
| 21797 | Woodbine | 8,643 | $189k | 6.5 mi |
| 20872 | Damascus | 13,983 | $141k | 7.1 mi |
| 21776 | New Windsor | 6,261 | $133k | 9.1 mi |
| 21791 | Union Bridge | 5,340 | $93k | 9.7 mi |
| 21701 | Frederick | 43,048 | $107k | 9.9 mi |
| 20882 | Gaithersburg | 13,751 | $184k | 11.5 mi |
| 21157 | Westminster | 38,984 | $105k | 14.1 mi |
| 21762 | Libertytown | 139 | – | 7.6 mi (near) |
| 21723 | Cooksville | 669 | $241k | 9.5 mi (near) |
| 21754 | Ijamsville | 8,156 | $182k | 9.5 mi (near) |
Source: PlainZIP from the Census 2020 ZCTA boundaries (shared edges) and internal points; figures ACS 2020-2024.