Residential delivery area · Maryland
ZIP Code 21104: Marriottsville, MD
ZIP code 21104 uses the postal name Marriottsville, Maryland and lies mostly in Howard County (53% of its land), reaching into Carroll County and Baltimore County (Census 2020 ZIP-county file). About 6,100 people live there (Census Bureau, ACS 2020-2024). Median household income is $191,804 (Census Bureau, ACS 2020-2024). By Census place, 32% of its land lies in Eldersburg (a census-designated place), and 3% in smaller places; 65% is outside any Census place.
- ACS2020-24
- Census2020
- FHFA2025
- ZBP2023
- IRS2022
- Town
- Marriottsville · its only residential ZIP
- County
- Howard County (53%); Carroll County (32%); Baltimore County (15%)
- Census places
- Eldersburg census-designated place
- Metro area
- Baltimore-Columbia-Towson, MD
- House districts
- MD-3 (53%), MD-2 (47%) 119th Congress, by share of land
- State
- Maryland
- Time zone
- Eastern
- Land area
- 17.1 sq mi · 355 people per sq mi
Where is ZIP code 21104?
21104 centers on 39.347°, -76.913° and covers 17.1 square miles of land plus 0.8 of water. It borders 7 ZIP codes: 21163, 21794, 21042, 21784, 21133, 21136, 21117.
The map draws ZIP code areas only. For the streets inside 21104, 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 21104 compare with the rest of Howard County?
| Measure | 21104 | In Howard County | In MD |
|---|---|---|---|
| People (ACS 2020-2024) | 6,052 | 17th of 25 | 224th of 477 |
| Median household income | $192k | 8th of 21 | 16th of 293 |
| Median home value | $680k | 11th of 23 | 32nd of 320 |
Its median household income is higher than in 99% 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 21104?
The 2020 Census counted 5,686 people in 21104; the ACS, which samples households over 2020-2024, estimates 6,052. Between the 2010 and 2020 censuses its population grew 23.6% (its boundary stayed at least 90% the same).
- People, ACS 2020-2024
- 6,052±883 (90% margin)
- 2020 Census count
- 5,686+23.6% since 2010 (4,601)
- Households
- 2,097
- Median age
- 43.1
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 21104?
Of the 6,052 people the ACS estimates in 21104, 20.7% are under 18 and 18.1% are 65 or older. The largest group by race and Hispanic origin is White (not Hispanic) (75.2%), then Asian (not Hispanic) (11.1%).
- Under 1820.7%
- 18 to 6461.3%
- 65 and older18.1%
- White, not Hispanic75.2%
- Asian, not Hispanic11.1%
- Other or two or more6.7%
- Black, not Hispanic5.9%
- Hispanic or Latino1.0%
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 21104 earn?
Median household income is $191,804 (ACS 2020-2024), the 8th highest of the 21 ranked ZIP codes in Howard County. It is not measurably different from 2015-2019 ($183,934 in 2024 dollars): the change is within the surveys' margins of error.
- Median household income
- $191,804
- Income per person
- $74,405
- Below the poverty line
- 2.7%
- Unemployed (of the labor force)
- 3.2%
- Adults 25+ with a bachelor's degree
- 64.4%
- Adjusted gross income per tax return, 2022
- $180,8802,960 returns; wages 66% 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 21104?
FHFA's house price index for 21104, built from repeat sales and appraisals of the same homes, rose 61% from 2015 to 2025 and rose 48% from 2020 to 2025, and moved +12.4% in 2025.
- Median home value (owners' estimate)
- $680,200
- Median gross rent
- $1,384
- Homes owned by their occupants
- 97.0%
- Housing units
- 2,204
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 21104?
157 business establishments had a location in this ZIP code in 2023, 17 more than in 2018; the most are in professional, scientific, and technical services (ZIP Code Business Patterns).
- Professional, scientific, and technical services40
- Construction20
- Health care and social assistance16
- Finance and insurance11
- Administrative and support and waste management and remediation services11
- Other services (except public administration)11
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 21104?
| ZIP | Town | People | Household income | Distance |
|---|---|---|---|---|
| 21163 | Woodstock | 7,539 | $135k | 3.5 mi |
| 21794 | West Friendship | 2,192 | $232k | 4.4 mi |
| 21042 | Ellicott City | 43,327 | $190k | 4.9 mi |
| 21784 | Sykesville | 39,258 | $139k | 5.0 mi |
| 21133 | Randallstown | 31,398 | $81k | 5.8 mi |
| 21136 | Reisterstown | 32,088 | $119k | 7.3 mi |
| 21117 | Owings Mills | 62,816 | $102k | 9.2 mi |
| 21723 | Cooksville | 669 | $241k | 5.0 mi (near) |
| 21244 | Windsor Mill | 38,208 | $85k | 7.3 mi (near) |
Source: PlainZIP from the Census 2020 ZCTA boundaries (shared edges) and internal points; figures ACS 2020-2024.