Residential delivery area · Maryland
ZIP Code 21778: Rocky Ridge, MD
ZIP code 21778 uses the postal name Rocky Ridge, Maryland and lies entirely in Frederick County (Census 2020 ZIP-county file). About 750 people live there (Census Bureau, ACS 2020-2024). Median household income is $76,458 (Census Bureau, ACS 2020-2024). Its land lies outside any incorporated or census-designated place.
- ACS2020-24
- Census2020
- FHFA2021
- ZBP2023
- IRS2022
- Town
- Rocky Ridge · its only residential ZIP
- County
- Frederick County
- Metro area
- Washington-Arlington-Alexandria, DC-VA-MD-WV
- House district
- MD-6 119th Congress
- State
- Maryland
- Time zone
- Eastern
- Land area
- 18.2 sq mi · 41 people per sq mi
Where is ZIP code 21778?
21778 centers on 39.616°, -77.328° and covers 18.2 square miles of land plus 0.4 of water. It borders 4 ZIP codes: 21757, 21788, 21727, 21798.
The map draws ZIP code areas only. For the streets inside 21778, 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).
How does 21778 compare with the rest of Frederick County?
| Measure | 21778 | In Frederick County | In MD |
|---|---|---|---|
| People (ACS 2020-2024) | 745 | 29th of 35 | 369th of 477 |
| Median household income | $77k | not ranked | not ranked |
| Median home value | $382k | not ranked | not ranked |
21778's income and home value are not ranked: it has fewer than 1,000 residents (745). Rankings use ZIP codes of 1,000 or more people living in households, with margins at most 25% of the figure.
It is denser than 38% of 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 21778?
The 2020 Census counted 1,145 people in 21778; the ACS, which samples households over 2020-2024, estimates 745. Between the 2010 and 2020 censuses its population grew 4.7% (its boundary stayed at least 90% the same).
- People, ACS 2020-2024
- 745±238 (90% margin)
- 2020 Census count
- 1,145+4.7% since 2010 (1,094)
- Households
- 332
- Median age
- 58.4
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 21778?
Of the 745 people the ACS estimates in 21778, 15.7% are under 18 and 33.7% are 65 or older. The largest group by race and Hispanic origin is White (not Hispanic) (100.0%).
- Under 1815.7%
- 18 to 6450.6%
- 65 and older33.7%
- White, not Hispanic100.0%
- Hispanic or Latino0.0%
- Black, not Hispanic0.0%
- Asian, not Hispanic0.0%
- Other or two or more0.0%
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 21778 earn?
Median household income is $76,458 (ACS 2020-2024). It is not measurably different from 2015-2019 ($91,257 in 2024 dollars): the change is within the surveys' margins of error.
- Median household income
- $76,458±$54,983
- Income per person
- $54,798
- Below the poverty line
- 0.9%
- Unemployed (of the labor force)
- 6.5%
- Adults 25+ with a bachelor's degree
- 27.0%
- Adjusted gross income per tax return, 2022
- $75,831550 returns; wages 71% 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 21778?
- Median home value (owners' estimate)
- $382,100
- Median gross rent
- –
- Homes owned by their occupants
- 81.3%
- Housing units
- 332
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 21778?
16 business establishments had a location in this ZIP code in 2023, 1 fewer than in 2018; the most are in construction (ZIP Code Business Patterns).
- Construction12
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 21778?
| ZIP | Town | People | Household income | Distance |
|---|---|---|---|---|
| 21757 | Keymar | 2,671 | $101k | 4.0 mi |
| 21788 | Thurmont | 11,654 | $99k | 4.9 mi |
| 21727 | Emmitsburg | 6,052 | $95k | 5.0 mi |
| 21798 | Woodsboro | 2,928 | $117k | 5.7 mi |
| 21780 | Sabillasville | 2,159 | $84k | 8.6 mi (near) |
| 21793 | Walkersville | 10,719 | $122k | 8.8 mi (near) |
| 21787 | Taneytown | 11,645 | $92k | 9.3 mi (near) |
| 21791 | Union Bridge | 5,340 | $93k | 9.4 mi (near) |
Source: PlainZIP from the Census 2020 ZCTA boundaries (shared edges) and internal points; figures ACS 2020-2024.