PlainZIP

Union Bridge, MD · standard

ZIP Code 21791

Carroll County, Maryland - Census ACS demographics, housing tenure, and business patterns, benchmarked against every US ZIP.

5,281
41/sq mi
$93,015
Median income
$379,800
Median home value
26.7%
Bachelor's or higher

The verdict

Union Bridge pairs an upper-quartile household income with upper-quartile home values, in a rural, homeowner-dominated area.

Top 24%
household income, US ZIPs
Top 23%
home value, US ZIPs
41
people per sq mi
82%
owner-occupied homes

Source: U.S. Census Bureau ACS 5-Year Estimates (2019–2023). Percentiles rank ZIP 21791 against every reporting US ZIP.

ZIP code 21791 is a mid-sized community (a standard USPS delivery area) in Union Bridge, Carroll County, Maryland, home to 5,281 residents across 127.6 square miles, a density of 41 people per square mile, in the New York time zone.

ZIP 21791 lands in the middle-income range, with a median household income of $93,015 (18% below the Maryland average), while per-capita income is $41,286. The poverty rate stands at 5.1% and the unemployment rate at 2.0%. The typical home here is valued at $379,800 (15% below the state average); renters pay a median of $1,457 monthly, and 81.7% of units are owner-occupied.

Educational attainment sits below the national norm: 26.7% of adults hold a bachelor's degree or higher, the median age is 37.7, and the average commute is 37 minutes. Beyond these figures, 10 nearby ZIP codes within about 10 miles are surfaced below, along with 6 more sharing Carroll County, letting you compare 21791 to its immediate surroundings rather than a national baseline alone.

Every figure on this page is sourced from the U.S. Census Bureau American Community Survey 5-Year Estimates (including median rent) and the FHFA House Price Index, no estimates, no proprietary scoring. Verify with Census →

Top industries in ZIP 21791

Top 5 sectors by establishment count in Union Bridge, MD

Which industries have the most business establishments in ZIP 21791.

establishments

What this shows Establishment counts come from the Census ZIP Code Business Patterns program, which counts physical business locations rather than employees or revenue.

Source U.S. Census Bureau · ZIP Code Business Patterns (ZBP) As of 2023

Source: U.S. Census Bureau, American Community Survey 5-Year Estimates + ZIP Code Business Patterns + FHFA HPI ACS demographics and median rent, ZBP business establishments, FHFA HPI for ZIP 21791, Union Bridge, MD · 2023 Census ACS 5-Year Estimates use a rolling 60-month sample for stable small-geography estimates; ZBP updated annually; FHFA HPI updated quarterly/annually.

Quick Facts

5,281

Population

127.6

Area (sq mi)

41

People / sq mi

New York

Time Zone

standard

ZIP Type

Neighborhood Scorecard
Get an A-F grade across income, safety, housing, rent, education, commute, and childcare for this ZIP code.
View Scorecard →

Who lives in ZIP 21791?

37.7

Median Age

50.7%

Male

49.3%

Female

2.2%

Foreign-Born

White 93.8%
African American 1.8%
Asian 3.1%
American Indian or Alaska Native 0.0%
Native Hawaiian or Pacific Islander 0.0%
Two or More Ethnicities 1.1%
Hispanic or Latino 1.1%

Hispanic or Latino is an ethnicity category from the Census Bureau and may overlap with other categories above.

Source: U.S. Census Bureau, ACS 5-Year Estimates (2023)

How much do residents earn?

$93,015

Median Household Income

-18% vs state

$41,286

Per Capita Income

5.1%

Poverty Rate

2.0%

Unemployment Rate

37.3 min

Mean Commute Time

How ZIP 21791 ranks nationally

Union Bridge, MD household income vs. every US ZIP code

Median household income, the full national distribution, with this ZIP marked

$93,015 Top 24% higher than 76% of 30,318 US ZIPs

$0–$20,000: 118 US ZIPs (0%). Below this entry. $20,000–$40,000: 1,573 US ZIPs (5%). Below this entry. $40,000–$60,000: 7,092 US ZIPs (23%). Below this entry. $60,000–$80,000: 9,980 US ZIPs (33%). Below this entry. $80,000–$100,000: 5,778 US ZIPs (19%). This entry sits in this band. $100,000–$120,000: 2,855 US ZIPs (9%). Above this entry. $120,000–$140,000: 1,362 US ZIPs (4%). Above this entry. $140,000–$160,000: 686 US ZIPs (2%). Above this entry. $160,000–$180,000: 364 US ZIPs (1%). Above this entry. $180,000–$200,000: 186 US ZIPs (1%). Above this entry. $200,000–$220,000: 324 US ZIPs (1%). Above this entry. This ZIP $0 $200K+ every reporting US ZIP, bucketed by value

Each bar is a $20K-wide band; taller bars hold more US ZIPs. The dashed line + filled bar mark this entry. Hover or tap any bar for its full count, share, and where it sits relative to this entry.

Source U.S. Census Bureau, ACS 5-Year Estimates · 2019–2023

Source: U.S. Census Bureau, ACS 5-Year Estimates (2023)

What is the education profile here?

High School Graduate or Higher 67.0%
Bachelor's Degree or Higher 26.7%

Source: U.S. Census Bureau, ACS 5-Year Estimates (2023)

What does housing look like?

2,059

Total Housing Units

1,968

Occupied Units

91

Vacant Units

2.71

Avg Household Size

Occupancy Type

Owner 81.7%
Renter 18.3%

$379,800

Median Home Value

-15% vs state

$1,457

Median Rent

1964

Median Year Built

Source: U.S. Census Bureau, ACS 5-Year Estimates (2023)

How have home values changed over time?

FHFA House Price Index, annual appreciation data based on repeat sales and appraisals

+9.4%

YoY Change (2024)

254

HPI Index (2000 = 100)

+154%

Total Change Since 2000

Home values in ZIP 21791 have increased 9.4% over the past year (2024). Since 2000, this ZIP has seen +154% cumulative appreciation.

Year Annual Change HPI Index
2020 +1.4% 168
2021 +10.1% 185
2022 +13.3% 210
2023 +10.5% 232
2024 +9.4% 254

Source: Federal Housing Finance Agency (FHFA) House Price Index, All-Transactions, Five-Digit ZIP Codes (Developmental Index). Index base = 100 in year 2000. Data through 2024. ZIP codes with few transactions may show missing values.

What businesses operate in this ZIP?

Census Bureau data shows 98 business establishments in ZIP 21791, employing approximately 868 people with a combined annual payroll of $40,869,000.

98

Businesses

868

Employees

$40.9M

Annual Payroll

11

Industry Sectors

Industry Establishments % of Total
Construction 33 33.7%
Other services (except public administration) 20 20.4%
Retail trade 7 7.1%
Transportation and warehousing 6 6.1%
Manufacturing 5 5.1%
Administrative and support and waste management and remediation services 5 5.1%
Health care and social assistance 5 5.1%
Professional, scientific, and technical services 4 4.1%
Accommodation and food services 4 4.1%
Agriculture, forestry, fishing and hunting 3 3.1%
Real estate and rental and leasing 3 3.1%

Source: U.S. Census Bureau, ZIP Code Business Patterns (ZBP), 2023. Employment figures may include noise for disclosure avoidance.

Nearby ZIP Codes

Want a side-by-side? Compare 21791 vs 21776 →

ZIP 21791 vs its nearest neighbors, by population

Resident population of this ZIP and the closest reporting ZIP codes within ~10 miles.

residents

What this shows Among its immediate neighbors, ZIP 21791 ranks #7 by population - useful context the national average alone can't give.

Source U.S. Census Bureau · ACS 5-Year Estimates As of 2019–2023

ZIP 21791 vs its nearest neighbors, by median income

Median household income of this ZIP and the closest reporting ZIP codes within ~10 miles.

median income

What this shows By household income, ZIP 21791 ranks #8 of 9 neighboring ZIPs, local affluence varies block to block, not just metro to metro.

Source U.S. Census Bureau · ACS 5-Year Estimates As of 2019–2023
ZIP Code City Population Distance
21776 New Windsor, MD 5,735 4.7 mi
21798 Woodsboro, MD 2,345 6.1 mi
21762 Libertytown, MD 249 5.2 mi
21757 Keymar, MD 3,036 5.6 mi
21787 Taneytown, MD 10,693 9.3 mi
21771 Mount Airy, MD 29,563 10.2 mi
21774 New Market, MD 11,662 10.2 mi
21778 Rocky Ridge, MD 1,094 9.5 mi
21701 Frederick, MD 35,293 10.2 mi
21727 Emmitsburg, MD 5,850 12.7 mi

More ZIP Codes in Carroll County

21784 standard
Sykesville, MD
Pop: 37,941
21157 standard
Westminster, MD
Pop: 36,920
21158 standard
Westminster, MD
Pop: 20,234
21074 standard
Hampstead, MD
Pop: 15,084
21102 standard
Manchester, MD
Pop: 11,751
21787 standard
Taneytown, MD
Pop: 10,693

Related Areas

Carroll County Union Bridge, MD Maryland

Frequently Asked Questions

What county is ZIP code 21791 in? ▼
ZIP code 21791 (Union Bridge) is located in Carroll County, Maryland. Carroll County contains multiple ZIP codes, see the full list at /counties/carroll-md.
What is the population of ZIP code 21791? ▼
ZIP code 21791 in Union Bridge, MD has a population of 5,281 according to the Census Bureau ACS 2023 estimates.
What is the median household income in ZIP 21791? ▼
The median household income in ZIP 21791 is $93,015, which is 22% above the national average of $76,288.
What is the average home value in ZIP 21791? ▼
The median home value in ZIP 21791 is $379,800, which is 37% above the national average of $278,155.
What is the demographic makeup of ZIP 21791? ▼
The largest racial group in ZIP 21791 is White at 93.8%. Hispanic or Latino residents make up 1.1% of the population.
How many businesses are in ZIP code 21791? ▼
ZIP code 21791 has 98 business establishments employing approximately 868 people, according to Census Bureau ZIP Code Business Patterns (ZBP) 2023 data.
What are the main industries in ZIP code 21791? ▼
The top industries by establishment count in ZIP 21791 are: Construction (33), Other services (except public administration) (20), Retail trade (7). There are 11 industry sectors represented in total.
How have home values changed in ZIP code 21791? ▼
According to the FHFA House Price Index, home values in ZIP 21791 increased by 9.4% in 2024. Since 2000, home values in this ZIP have appreciated by approximately 154%. This is a developmental index based on repeat sales and appraisal data from Fannie Mae and Freddie Mac.
What is the education level in ZIP code 21791? ▼
In ZIP code 21791, 67.0% of residents aged 25+ have a high school diploma or higher, and 26.7% hold a bachelor's degree or higher. These figures come from the Census Bureau ACS 5-Year Estimates (2023).
What is the average commute time in ZIP 21791? ▼
The mean commute time for workers in ZIP code 21791 is 37.3 minutes according to Census ACS data. The national average is roughly 26 minutes, so commuters here spend more time traveling to work than typical.
What percentage of residents own vs. rent in ZIP 21791? ▼
In ZIP code 21791, approximately 81.7% of occupied housing units are owner-occupied and 18.3% are renter-occupied, based on Census ACS 2023 data.
What is the poverty rate in ZIP code 21791? ▼
The poverty rate in ZIP code 21791 is 5.1% according to Census Bureau ACS 2023 estimates. This measures the percentage of the population living below the federal poverty threshold.

Read our methodology to see how this data is sourced, computed, and verified.