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 Moderate-density area
- $93,015
- Median income Above-median income area
- $379,800
- Median home value Above-median home value
- 26.7%
- Bachelor's or higher Near-average bachelor's attainment
National ZIP placement
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.
FHFA HPI release change
What changed in the latest House Price Index year
- FHFA House Price Index values in ZIP 21791 (Union Bridge, MD) rose +9.4% from 2023 to 2024. The all-transactions index moved from 231.8 in 2023 to 253.6 in 2024 (2000 = 100).
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 average Maryland ZIP), while per-capita income is $41,286. Both reported hardship measures are comparatively low in absolute terms: poverty is 5.1% and unemployment is 2.0%. Home values sit below the statewide ZIP benchmark: the median is $379,800 (15% below the average Maryland ZIP), and median rent is $1,457; owner occupancy is 81.7%.
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. The page also surfaces 10 ZIP codes within roughly 10 miles and 6 more in Carroll County, so 21791 can be compared with both its immediate and county-level context.
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.
- Construction
Construction
33 establishments
- Other services (except public administration)
Other services (except public administration)
20 establishments
- Retail trade 7
Retail trade
7 establishments
- Transportation and warehousing 6
Transportation and warehousing
6 establishments
- Manufacturing 5
Manufacturing
5 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, 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
Who lives in ZIP 21791?
37.7
Median Age
50.7%
Male
49.3%
Female
2.2%
Foreign-Born
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 ZIP avg
$41,286
Per Capita Income
5.1%
Poverty Rate
2.0%
Unemployment Rate
37.3 min
Mean Commute Time
How ZIP 21791 ranks among Maryland ZIPs
Union Bridge, MD household income vs. every Maryland ZIP code
Median household income among 419 reporting Maryland ZIPs (this ZIP's population is too small for a reliable national-corpus placement)
$93,015 41st percentile higher than 41% of 419 Maryland ZIPs
Each bar is a $20K-wide band; taller bars hold more Maryland 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?
Source: U.S. Census Bureau, ACS 5-Year Estimates (2023)
What does housing look like?
Housing stock: occupied vs vacant
2,059housing units
2,059
Total Housing Units
1,968
Occupied Units
91
Vacant Units
2.71
Avg Household Size
Occupancy Type
$379,800
Median Home Value
-15% vs state ZIP avg
$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.
- 21701
Frederick (21701)
35,293 residents
- 21771
Mount Airy (21771)
29,563 residents
- 21774 11,662
New Market (21774)
11,662 residents
- 21787 10,693
Taneytown (21787)
10,693 residents
- 21727 5,850
Emmitsburg (21727)
5,850 residents
- 21776 5,735
New Windsor (21776)
5,735 residents
- 21791 5,281
Union Bridge (21791)
5,281 residents
- 21757 3,036
Keymar (21757)
3,036 residents
- 21798 2,345
Woodsboro (21798)
2,345 residents
What this shows Among its immediate neighbors, ZIP 21791 ranks #7 by population - useful context the national average alone can't give.
ZIP 21791 vs its nearest neighbors, by median income
Median household income of this ZIP and the closest reporting ZIP codes within ~10 miles.
- 21774
New Market (21774)
$171,103 median income
- 21771
Mount Airy (21771)
$157,302 median income
- 21776
New Windsor (21776)
$133,409 median income
- 21798
Woodsboro (21798)
$116,607 median income
- 21701
Frederick (21701)
$106,577 median income
- 21757
Keymar (21757)
$100,500 median income
- 21727
Emmitsburg (21727)
$95,236 median income
- 21791
Union Bridge (21791)
$93,015 median income
- 21787
Taneytown (21787)
$91,682 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.
| 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 |
Nationwide ZIPs with similar ACS profiles
Two Census-derived peer sets for ZIP 21791, both outside MD so the neighborhoods are not geographic containment (Nearby and same-county blocks stay local).
Similar population
Nearest cross-state ZIPs by resident population (5,281 here; floor ≥1,000).
Similar median household income
Nearest cross-state ZIPs by ACS median household income.
More ZIP Codes in Carroll County
Related Areas
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.
Related
Take this with you
What to do with ZIP 21791's numbers, next.
- See how ZIP 21791 compares to a neighboring ZIP code on the same Census fields Compare this ZIP
- Check where Union Bridge, MD ranks among every U.S. ZIP code on income, education, or homeownership View national rankings
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ZIP Code Tabulation Areas (ZCTAs) are Census Bureau approximations of USPS ZIP codes; figures describe the ZCTA area, not any single address within it.