Residential delivery area · Maryland
ZIP Code 21758: Knoxville, MD
ZIP code 21758 uses the postal name Knoxville, Maryland and lies mostly in Frederick County (50% of its land) with the rest in Washington County (Census 2020 ZIP-county file). About 4,400 people live there (Census Bureau, ACS 2020-2024). Median household income is $111,528 (Census Bureau, ACS 2020-2024). By Census place, its land lies in Garretts Mill (2%), Rosemont (2%), Sandy Hook (under 1%) and Yarrowsburg (under 1%), and 2% in smaller places; 93% is outside any Census place.
- ACS2020-24
- Census2020
- FHFA2025
- ZBP2023
- IRS2022
- Town
- Knoxville · its only residential ZIP
- County
- Frederick County (50%); Washington County (50%)
- Census places
- Garretts Mill (2%) census-designated place; Rosemont (2%); Sandy Hook (under 1%) census-designated place; Yarrowsburg (under 1%) census-designated place
- Metro area
- Washington-Arlington-Alexandria, DC-VA-MD-WV
- House district
- MD-6 119th Congress
- State
- Maryland
- Time zone
- Eastern
- Land area
- 32.0 sq mi · 138 people per sq mi
Where is ZIP code 21758?
21758 centers on 39.353°, -77.657° and covers 32.0 square miles of land plus 2.8 of water. It borders 8 ZIP codes: 21715, 21716, 21755, 21779, 20180, 25425, 21782, 20132.
The map draws ZIP code areas only. For the streets inside 21758, 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 21758 compare with the rest of Frederick County?
| Measure | 21758 | In Frederick County | In MD |
|---|---|---|---|
| People (ACS 2020-2024) | 4,409 | 22nd of 35 | 248th of 477 |
| Median household income | $112k | 15th of 26 | 145th of 293 |
| Median home value | $425k | 20th of 28 | 165th of 320 |
Its median household income is higher than in 87% of U.S. residential ZIP codes, and it is denser than 58% 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 21758?
The 2020 Census counted 4,809 people in 21758; the ACS, which samples households over 2020-2024, estimates 4,409. Between the 2010 and 2020 censuses its population fell 2.3% (its boundary stayed at least 90% the same).
- People, ACS 2020-2024
- 4,409±763 (90% margin)
- 2020 Census count
- 4,809−2.3% since 2010 (4,921)
- Households
- 1,588
- Median age
- 39.0
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 21758?
Of the 4,409 people the ACS estimates in 21758, 24.2% are under 18 and 17.7% are 65 or older. The largest group by race and Hispanic origin is White (not Hispanic) (81.1%).
- Under 1824.2%
- 18 to 6458.1%
- 65 and older17.7%
- White, not Hispanic81.1%
- Hispanic or Latino9.0%
- Other or two or more4.8%
- Black, not Hispanic2.9%
- Asian, not Hispanic2.0%
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 21758 earn?
Median household income is $111,528 (ACS 2020-2024), the 15th highest of the 26 ranked ZIP codes in Frederick County. It is not measurably different from 2015-2019 ($99,233 in 2024 dollars): the change is within the surveys' margins of error.
- Median household income
- $111,528±$18,951
- Income per person
- $50,488
- Below the poverty line
- 5.9%
- Unemployed (of the labor force)
- 8.5%
- Adults 25+ with a bachelor's degree
- 43.7%
- Adjusted gross income per tax return, 2022
- $93,6622,340 returns; wages 72% 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 21758?
FHFA's house price index for 21758, built from repeat sales and appraisals of the same homes, rose 89% from 2015 to 2025 and rose 60% from 2020 to 2025, and moved +19.5% in 2025.
- Median home value (owners' estimate)
- $424,600
- Median gross rent
- $1,770
- Homes owned by their occupants
- 84.4%
- Housing units
- 1,626
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 21758?
59 business establishments had a location in this ZIP code in 2023, 4 more than in 2018; the most are in construction (ZIP Code Business Patterns).
- Construction16
- Other services (except public administration)12
- Professional, scientific, and technical services10
- Administrative and support and waste management and remediation services6
- Retail trade4
- Accommodation and food services4
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 21758?
| ZIP | Town | People | Household income | Distance |
|---|---|---|---|---|
| 21715 | Brownsville | 20 | – | 1.8 mi |
| 21716 | Brunswick | 7,200 | $109k | 2.9 mi |
| 21755 | Jefferson | 5,909 | $137k | 4.8 mi |
| 21779 | Rohrersville | 1,311 | – | 4.9 mi |
| 20180 | Lovettsville, VA | 7,531 | $152k | 5.9 mi |
| 25425 | Harpers Ferry, WV | 13,332 | $94k | 7.0 mi |
| 21782 | Sharpsburg | 3,704 | $94k | 9.0 mi |
| 20132 | Purcellville, VA | 19,817 | $182k | 13.5 mi |
| 21718 | Burkittsville | 134 | $94k | 3.2 mi (near) |
| 21756 | Keedysville | 3,640 | $102k | 7.6 mi (near) |
Source: PlainZIP from the Census 2020 ZCTA boundaries (shared edges) and internal points; figures ACS 2020-2024.