21791 ZIP Code — Union Bridge, MD

Carroll County, Maryland

ZIP code 21791 is located in Union Bridge, Maryland, within Carroll County. It covers approximately 46.04 square miles and serves a population of 4,855 residents. This is a standard ZIP code in the Eastern (ET) timezone, served by area code 443/410/667.

About ZIP code 21791

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 $349,900. Owner-occupancy is high at 81%, well above the national average.

Median household income is $88,984. 33% of households receive Social Security income, suggesting a notable retiree or disability population.

The dominant occupation class is management, business, and professional, with professional and management as the leading industry. An above-average commute of 37 minutes suggests many residents work outside the immediate area.

Educational attainment is near the national average, with 26% of residents holding a bachelor's degree or higher.

Notable community characteristics include a notable veteran presence at 13% of civilians, above the national average of 7%.

Overall, ZIP code 21791 reflects a community defined by a strong veteran community, high homeownership, and a significant Social Security-dependent population.

4,855

population

46.04

sq mi land

Standard

ZIP type

Eastern (ET)

timezone

21791 ZIP code map

Cities in ZIP code 21791

Below are the cities the US Postal Service accepts for ZIP code 21791. Using any city not on this list may result in mail delivery delays.

City	Status
Union Bridge	Acceptable
Union Bridge	Preferred

Nearby ZIP codes

21776 New Windsor (4.6 mi) 21757 Keymar (5.5 mi) 21798 Woodsboro (5.8 mi) 21787 Taneytown (8.6 mi) 21793 Walkersville (8.8 mi) 21701 Frederick (9.4 mi) 21778 Rocky Ridge (9.5 mi) 21774 New Market (9.5 mi) 21157 Westminster (10.6 mi) 21771 Mount Airy (11.1 mi) 21158 Westminster (11.2 mi) 21727 Emmitsburg (12.7 mi)

Demographics updated 05/2026

Population
Total population	4,855
Population density	105 / sq mi
State FIPS	24
County FIPS	013

Geography
Land area	46.04 sq mi
Water area	0.08 sq mi
Latitude	39.5328
Longitude	-77.1873
Timezone	Eastern (ET)
Area code	443/410/667

Total population by age

Gender

Race & ethnicity

Economics updated 05/2026

Household income

Income range	This ZIP	County avg	State avg
Under $50k	26.2%	23.8%	28.2%
$50k – $100k	28.3%	26.3%	28.2%
$100k – $200k	37.4%	37.1%	30.1%
Over $200k	8.1%	12.8%	13.4%

Demographics & statistics

4,855

Population

105

People per sq mi

42.6

Median age

$88,984

Median household income

$42,725

Per capita income

$349,900

Median home value

$1,156

Median monthly rent

81.4%

Home ownership

9.8%

Poverty rate

2.6%

Unemployment

1,640

Housing units

25.9%

Bachelor's or higher

Age distribution

Male Female

155

Under 5

131

5–9

149

10–14

126

213

15–19

180

152

20–24

129

326

25–34

276

327

35–44

277

300

45–54

254

213

55–59

179

220

60–64

186

253

65–74

213

132

75–84

112

110

85+

← Male

Female →

Age summary

Group	Count	%
Under 18	989	20.4%
18 and over	3,866	79.6%
65 and over	912	18.8%
Median age	42.6 years

Race & ethnicity

White 94.5%

Asian 1.7%

Two or more races 1.3%

Black or African American 1.1%

Hispanic or Latino 0.6%

Other race 0.5%

Native Hawaiian / Pacific Islander 0.2%

American Indian / Alaska Native 0.1%

Group	Count	%
White	4,617	94.5%
Asian	81	1.7%
Two or more races	63	1.3%
Black or African American	53	1.1%
Hispanic or Latino	30	0.6%
Other race	26	0.5%
Native Hawaiian / Pacific Islander	10	0.2%
American Indian / Alaska Native	5	0.1%

Household income

Income range	This ZIP	County avg	State avg
Under $50k	26.2%	23.8%	28.2%
$50k – $100k	28.3%	26.3%	28.2%
$100k – $200k	37.4%	37.1%	30.1%
Over $200k	8.1%	12.8%	13.4%

Under $10k 1.4%

$10k–$15k 3.4%

$15k–$25k 4.5%

$25k–$35k 5.2%

$35k–$50k 7.9%

$50k–$75k 19.8%

$75k–$100k 11.3%

$100k–$150k 21.9%

$150k–$200k 14.4%

$200k+ 10.1%

Range	% of households
Under $10k	1.4%
$10k–$15k	3.4%
$15k–$25k	4.5%
$25k–$35k	5.2%
$35k–$50k	7.9%
$50k–$75k	19.8%
$75k–$100k	11.3%
$100k–$150k	21.9%
$150k–$200k	14.4%
$200k+	10.1%
Median income	$88,984

Housing

Home values

Under $50k 1.8%

$50k–$100k 0.2%

$100k–$150k 4.7%

$150k–$200k 6.8%

$200k–$300k 22.5%

$300k–$500k 40.9%

$500k–$1M 19.5%

$1M+ 3.6%

Housing overview

Metric	Value
Median home value	$349,900
Median rent / month	$1,156
Owner occupied	81.4%
Renter occupied	18.6%
Vacant	5.5%
Single-family detached	90.5%
Large apartment buildings	0.0%
Mobile homes	0.4%
Median rooms	6.9
Avg household size (owned)	2.67

Year built

Era	%
2020 or later	0.6%
2010–2019	1.6%
2000–2009	6.4%
1990–1999	5.8%
1980–1989	8.9%
1970–1979	13.6%
1960–1969	15.5%
1950–1959	4.2%
1940–1949	5.7%
1939 or earlier	37.7%

Bedrooms

Size	% of units
No bedroom (studio)	0.2%
1 bedroom	5.5%
2 bedrooms	18.1%
3 bedrooms	48.4%
4 bedrooms	21.8%
5+ bedrooms	6.1%

Vehicles per household

Vehicles	% of households
No vehicle	2.1%
1 vehicle	19.7%
2 vehicles	31.8%
3 or more	46.4%

Heating fuel

Fuel type	%
Utility gas	1.2%
Electricity	39.3%
Propane / LP gas	7.0%
Fuel oil	36.6%
Wood	12.5%
No fuel used	1.2%

Households & families

Household type	Count	%
Married-couple family	1,057	56.3%
Cohabiting couple	167	8.9%
Male householder, no spouse	416	22.1%
Female householder, no spouse	239	12.7%
Households with children under 18	561	29.9%
Households with seniors (65+)	612	32.6%
Average household size	2.58

Marital status

Status	Male	Female
Never married	35.6%	23.0%
Married	51.2%	57.2%
Separated	0.4%	0.9%
Widowed	3.6%	5.0%
Divorced	9.2%	13.8%

Education

Less than 9th grade 3.5%

Some HS, no diploma 3.6%

HS graduate 44.1%

Some college, no degree 19.9%

Associate's degree 3.0%

Bachelor's degree 15.1%

Graduate / professional 10.8%

Metric	%
HS diploma or higher	92.9%
Bachelor's or higher	25.9%

School enrollment (ages 3–17)

Type	Count	%
Nursery / preschool	48	5.1%
Kindergarten	21	2.2%
Elementary school	388	41.2%
High school	334	35.5%
College / grad school	151	16.0%

Employment

Industry of employment

Professional & management 15.5%

Construction 13.5%

Education & healthcare 10.6%

Public administration 10.0%

Retail trade 9.5%

Arts, food & hospitality 7.4%

Other services 7.2%

Manufacturing 7.0%

Transportation & utilities 6.5%

Agriculture & mining 5.8%

Finance & real estate 3.9%

Information 2.0%

Wholesale trade 1.1%

Occupation

Category	%
Management, business & arts	32.3%
Service	21.4%
Sales & office	16.7%
Natural resources & construction	16.3%
Production & transportation	13.2%

Employment type

Type	%
Private sector	68.1%
Government	20.5%
Self-employed	9.1%
Unpaid family workers	2.2%

Commute

Method	%
Drive alone	86.3%
Carpool	4.2%
Public transit	0.0%
Walk	1.4%
Work from home	7.8%
Other means	0.2%
Avg commute (minutes)	37.2

Poverty

All people 9.8%

Under 18 years 11.6%

18 and over 9.3%

Married-couple families 1.8%

Female-led households 43.3%

Income support

Source	% of households
Social Security	32.7%
Retirement income	25.7%
Supplemental Security	4.0%
Cash public assistance	3.0%
Food stamps / SNAP	8.1%

Health indicators

Condition	%
Obesity	32.5%
High blood pressure	34.6%
High cholesterol	36.5%
Diabetes	10.3%
Heart disease	6.3%
Stroke	2.9%
Asthma	9.7%
Arthritis	26.3%
Kidney disease	2.8%
Pulmonary disease	6.8%
Cancer	7.3%

Behavior / access	%
Smoking	16.1%
Binge drinking	16.1%
No physical activity	21.4%
Less than 7 hrs sleep	29.9%
Depression	19.9%
Fair or poor health	12.3%
Poor mental health	14.1%
Poor physical health	9.2%
No health insurance	9.6%
Visited doctor (checkup)	76.5%
Visited dentist	66.1%
Cholesterol screening	91.9%
Teeth loss	11.2%

Veterans & disability

Veterans	Count	%
Civilian veterans	511	13.2%

Disability	%
Any disability	12.9%
Under 18	2.4%
18–64 years	13.6%
65 and over	21.7%

Health insurance coverage

Type	%
Private insurance	75.2%
Public insurance	35.8%
No insurance	6.5%
Uninsured under 19	6.5%

Language & origin

Language spoken at home (age 5+)

Language	Count	%
English only	4,569	94.1%
Spanish	35	0.8%
Other Indo-European	19	0.4%
Asian & Pacific Islander	10	0.2%
Other languages	6	0.1%

Place of birth & citizenship

Origin	Count	%
Native born (US)	4,743	97.7%
Born in same state	4,727	97.4%
Born in different state	3,316	68.3%
Foreign born	16	0.3%
Naturalized citizen	112	2.3%
Not a US citizen	82	73.2%

Ancestry

Ancestry	Count	%
Arab	1,095	22.6%
Italian	646	13.3%
French	627	12.9%
Irish	10	0.2%

Ancestry	Count	%
German	8	0.2%
English	6	0.1%
Polish	5	0.1%

Technology access

Metric	% of households
Computer access	38.7%
Internet access	88.8%

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

Frequently asked questions about ZIP code 21791

What city is ZIP code 21791 in?

ZIP code 21791 is primarily assigned to Union Bridge, Maryland.

What county is ZIP code 21791 in?

ZIP code 21791 falls within Carroll County, Maryland.

Is ZIP code 21791 mostly owner-occupied?

81% of occupied units in ZIP code 21791 are owner-occupied, well above the national average.

Does ZIP code 21791 have a large veteran population?

13% of civilians in ZIP code 21791 are veterans, above the national average of ~7%.

What is the typical home value in ZIP code 21791?

The median home value in ZIP code 21791 is $349,900.

What is the population of ZIP code 21791?

ZIP code 21791 has an estimated population of 4,855 residents, with a density of 105 people per square mile.

What timezone is ZIP code 21791 in?

ZIP code 21791 observes the EST timezone.