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Zip Code 21791 — Union Bridge, MD

21791 is a ZIP Code associated with Union Bridge, MD, located within Frederick. The postal region supports an estimated population of 5,340 residents across Data Pending housing units, with a population density of 44.8 people per square mile.

WorldPlaceData database updated: October 2026

📍 View location on OpenStreetMap (39.542670, -77.187130)

Data Metric	Local Statistic
Postal / Zip Code	21791
Primary City	Union Bridge
State / Province	MD
County	Frederick
Total Population	5,340
Median Household Income	Data Pending
Total Housing Units	Data Pending
Population Density	44.8 people/sq mi
Timezone	America/New_York

How 21791 Compares

Metric	ZIP 21791	Frederick County	MD State Average
Population	5,340	300,100	6,205,597
Median Income	Data Pending	N/A	N/A
Population Density	44.8 /sq mi	--	--

Nearby ZIP Codes

ZIP Code	City	Distance	Population	Median Income
Zip 21776	New Windsor	4.7 mi	6,261	N/A
Zip 21762	Libertytown	5.4 mi	139	N/A
Zip 21757	Keymar	5.5 mi	2,671	N/A
Zip 21798	Woodsboro	6.0 mi	2,928	N/A
Zip 21787	Taneytown	8.9 mi	11,645	N/A

Data Sources & Methodology: Geographic coordinates and ZIP Code assignments are derived from underlying geographic and postal datasets. Note that ZIP Codes are USPS postal delivery areas, while Census ZCTAs are statistical approximation areas. Read full methodology →