21758 ZIP Code — Knoxville, MD

Frederick County, Maryland

ZIP code 21758 is located in Knoxville, Maryland, within Frederick County. It covers approximately 32.02 square miles and serves a population of 4,610 residents. This is a standard ZIP code in the Eastern (ET) timezone, served by area code 240/301.

About ZIP code 21758

The housing stock consists of predominantly single-family detached homes. Most homes were built in the pre-1940, giving the area an established character. Median home value is $338,000. Owner-occupancy is high at 88%, well above the national average.

Median household income is $103,081. The poverty rate of 5% is below the national average. 32% of households receive Social Security income, suggesting a notable retiree or disability population.

The dominant occupation class is management, business, and professional, with education and healthcare as the leading industry. An above-average commute of 40 minutes suggests many residents work outside the immediate area.

Educational attainment is near the national average, with 37% of residents holding a bachelor's degree or higher.

Overall, ZIP code 21758 reflects a community defined by high homeownership and a significant Social Security-dependent population.

4,610

population

32.02

sq mi land

Standard

ZIP type

Eastern (ET)

timezone

21758 ZIP code map

Cities in ZIP code 21758

Below are the cities the US Postal Service accepts for ZIP code 21758. Using any city not on this list may result in mail delivery delays.

City	Status
Knoxville	Acceptable
Knoxville	Preferred

Nearby ZIP codes

21718 Burkittsville (2.8 mi) 21716 Brunswick (3.8 mi) 21779 Rohrersville (4.3 mi) 21755 Jefferson (4.7 mi) 21756 Keedysville (6.5 mi) 20180 Lovettsville (6.6 mi) 20103 Dulles (7.3 mi) 20104 Dulles (7.3 mi) 21769 Middletown (7.5 mi) 21782 Sharpsburg (8.2 mi) 21777 Point Of Rocks (9 mi) 25442 Shenandoah Junction (9 mi)

Demographics updated 05/2026

Population
Total population	4,610
Population density	144 / sq mi
State FIPS	24
County FIPS	021

Geography
Land area	32.02 sq mi
Water area	2.83 sq mi
Latitude	39.3616
Longitude	-77.6619
Timezone	Eastern (ET)
Area code	240/301

Total population by age

Gender

Race & ethnicity

Economics updated 05/2026

Household income

Income range	This ZIP	County avg	State avg
Under $50k	22.1%	22.0%	28.2%
$50k – $100k	27.5%	27.2%	28.2%
$100k – $200k	43.7%	36.5%	30.1%
Over $200k	6.7%	14.3%	13.4%

Demographics & statistics

4,610

Population

144

People per sq mi

39.0

Median age

$103,081

Median household income

$46,264

Per capita income

$338,000

Median home value

$1,688

Median monthly rent

87.5%

Home ownership

5.1%

Poverty rate

7.2%

Unemployment

1,522

Housing units

36.8%

Bachelor's or higher

Age distribution

Male Female

200

Under 5

200

128

5–9

128

164

10–14

163

112

15–19

112

114

20–24

113

311

25–34

310

276

35–44

275

302

45–54

300

134

55–59

134

112

60–64

111

244

65–74

243

160

75–84

160

85+

← Male

Female →

Age summary

Group	Count	%
Under 18	1,111	24.1%
18 and over	3,499	75.9%
65 and over	911	19.8%
Median age	39.0 years

Race & ethnicity

White 76.8%

Two or more races 7.9%

Hispanic or Latino 6.8%

Black or African American 6%

Asian 2.3%

American Indian / Alaska Native 0.1%

Other race 0.1%

Group	Count	%
White	3,799	76.8%
Two or more races	389	7.9%
Hispanic or Latino	339	6.8%
Black or African American	297	6%
Asian	114	2.3%
American Indian / Alaska Native	6	0.1%
Other race	5	0.1%

Household income

Income range	This ZIP	County avg	State avg
Under $50k	22.1%	22.0%	28.2%
$50k – $100k	27.5%	27.2%	28.2%
$100k – $200k	43.7%	36.5%	30.1%
Over $200k	6.7%	14.3%	13.4%

Under $10k 1.7%

$10k–$15k 3.7%

$15k–$25k 2.5%

$25k–$35k 2.8%

$35k–$50k 4.5%

$50k–$75k 17.5%

$75k–$100k 15.6%

$100k–$150k 23.8%

$150k–$200k 17.1%

$200k+ 10.7%

Range	% of households
Under $10k	1.7%
$10k–$15k	3.7%
$15k–$25k	2.5%
$25k–$35k	2.8%
$35k–$50k	4.5%
$50k–$75k	17.5%
$75k–$100k	15.6%
$100k–$150k	23.8%
$150k–$200k	17.1%
$200k+	10.7%
Median income	$103,081

Housing

Home values

Under $50k 3.4%

$50k–$100k 2.4%

$100k–$150k 1.8%

$150k–$200k 6.6%

$200k–$300k 31.0%

$300k–$500k 33.6%

$500k–$1M 18.5%

$1M+ 2.8%

Housing overview

Metric	Value
Median home value	$338,000
Median rent / month	$1,688
Owner occupied	87.5%
Renter occupied	12.5%
Vacant	2.1%
Single-family detached	86.5%
Large apartment buildings	0.0%
Mobile homes	0.0%
Median rooms	6.9
Avg household size (owned)	2.66

Year built

Era	%
2020 or later	0.0%
2010–2019	2.1%
2000–2009	22.1%
1990–1999	5.8%
1980–1989	14.6%
1970–1979	11.7%
1960–1969	6.3%
1950–1959	12.1%
1940–1949	2.0%
1939 or earlier	23.2%

Bedrooms

Size	% of units
No bedroom (studio)	0.0%
1 bedroom	2.3%
2 bedrooms	24.9%
3 bedrooms	38.4%
4 bedrooms	19.3%
5+ bedrooms	15.2%

Vehicles per household

Vehicles	% of households
No vehicle	3.9%
1 vehicle	17.9%
2 vehicles	36.5%
3 or more	41.7%

Heating fuel

Fuel type	%
Utility gas	18.6%
Electricity	32.6%
Propane / LP gas	10.1%
Fuel oil	26.1%
Wood	10.3%
Solar	0.2%

Households & families

Household type	Count	%
Married-couple family	965	56.9%
Cohabiting couple	87	5.1%
Male householder, no spouse	274	16.1%
Female householder, no spouse	371	21.9%
Households with children under 18	538	31.7%
Households with seniors (65+)	681	40.1%
Average household size	2.71

Marital status

Status	Male	Female
Never married	27.4%	23.4%
Married	55.8%	54.8%
Separated	2.6%	0.5%
Widowed	4.6%	9.3%
Divorced	9.6%	12.0%

Education

Less than 9th grade 1.7%

Some HS, no diploma 3.8%

HS graduate 36.1%

Some college, no degree 15.1%

Associate's degree 6.5%

Bachelor's degree 19.7%

Graduate / professional 17.0%

Metric	%
HS diploma or higher	94.5%
Bachelor's or higher	36.8%

School enrollment (ages 3–17)

Type	Count	%
Nursery / preschool	40	4.0%
Kindergarten	51	5.1%
Elementary school	460	45.9%
High school	205	20.5%
College / grad school	246	24.6%

Employment

Industry of employment

Education & healthcare 20.1%

Professional & management 17.0%

Arts, food & hospitality 9.7%

Public administration 8.4%

Other services 8.3%

Construction 8.1%

Retail trade 7.4%

Manufacturing 6.3%

Finance & real estate 5.2%

Agriculture & mining 3.2%

Wholesale trade 2.9%

Information 2.0%

Transportation & utilities 1.4%

Occupation

Category	%
Management, business & arts	42.7%
Service	17.4%
Sales & office	17.7%
Natural resources & construction	9.3%
Production & transportation	12.8%

Employment type

Type	%
Private sector	76.8%
Government	17.8%
Self-employed	5.3%
Unpaid family workers	0.0%

Commute

Method	%
Drive alone	77.0%
Carpool	5.8%
Public transit	4.0%
Walk	1.0%
Work from home	12.1%
Other means	0.0%
Avg commute (minutes)	40.2

Poverty

All people 5.1%

Under 18 years 0.1%

18 and over 6.6%

Married-couple families 2.7%

Female-led households 0.8%

Income support

Source	% of households
Social Security	32.4%
Retirement income	28.9%
Supplemental Security	3.1%
Cash public assistance	4.3%
Food stamps / SNAP	8.4%

Health indicators

Condition	%
Obesity	32.8%
High blood pressure	32.2%
High cholesterol	34.2%
Diabetes	9.3%
Heart disease	5.3%
Stroke	2.4%
Asthma	9.7%
Arthritis	23.8%
Kidney disease	2.4%
Pulmonary disease	5.4%
Cancer	6.8%

Behavior / access	%
Smoking	13.9%
Binge drinking	16.3%
No physical activity	19.6%
Less than 7 hrs sleep	31.7%
Depression	19.7%
Fair or poor health	10.0%
Poor mental health	13.4%
Poor physical health	7.9%
No health insurance	8.4%
Visited doctor (checkup)	76.2%
Visited dentist	70.4%
Cholesterol screening	92.9%
Teeth loss	8.8%

Veterans & disability

Veterans	Count	%
Civilian veterans	277	7.9%

Disability	%
Any disability	9.1%
Under 18	0.8%
18–64 years	5.4%
65 and over	29.7%

Health insurance coverage

Type	%
Private insurance	80.5%
Public insurance	31.2%
No insurance	4.0%
Uninsured under 19	3.5%

Language & origin

Language spoken at home (age 5+)

Language	Count	%
English only	4,210	91.3%
Spanish	105	2.5%
Other Indo-European	77	1.8%
Asian & Pacific Islander	5	0.1%
Other languages	23	0.5%

Place of birth & citizenship

Origin	Count	%
Native born (US)	4,292	93.1%
Born in same state	4,227	91.7%
Born in different state	2,173	47.1%
Foreign born	65	1.4%
Naturalized citizen	318	6.9%
Not a US citizen	183	57.5%

Ancestry

Ancestry	Count	%
French	736	16%
Italian	706	15.3%
Arab	249	5.4%
English	49	1.1%

Ancestry	Count	%
Polish	23	0.5%
German	18	0.4%
Irish	5	0.1%
Norwegian	1	0%

Technology access

Metric	% of households
Computer access	36.8%
Internet access	94.2%

Source: U.S. Census Bureau, American Community Survey 2025 estimates.

Frequently asked questions about ZIP code 21758

What city is ZIP code 21758 in?

ZIP code 21758 is primarily assigned to Knoxville, Maryland.

What county is ZIP code 21758 in?

ZIP code 21758 falls within Frederick County, Maryland.

Is ZIP code 21758 mostly owner-occupied?

88% of occupied units in ZIP code 21758 are owner-occupied, well above the national average.

What is the typical home value in ZIP code 21758?

The median home value in ZIP code 21758 is $338,000.

What is the median household income in ZIP code 21758?

The median household income in ZIP code 21758 is $103,081, above the national median of ~$75,000.

What is the population of ZIP code 21758?

ZIP code 21758 has an estimated population of 4,610 residents, with a density of 144 people per square mile.

What timezone is ZIP code 21758 in?

ZIP code 21758 observes the EST timezone.