Great Mills, MD · standard
ZIP Code 20634
St. Mary's County, Maryland - Census ACS demographics, housing tenure, and business patterns, benchmarked against every US ZIP.
- 5,927
- 333/sq mi High-density area
- $139,375
- Median income Above-median income area
- $342,300
- Median home value Above-median home value
- 40.3%
- Bachelor's or higher Above-average bachelor's attainment
National ZIP placement
Great Mills pairs a top-decile household income with above-median home values, in a low-density, homeowner-dominated area.
- Top 5%
- household income, US ZIPs
- Top 27%
- home value, US ZIPs
- 333
- people per sq mi
- 65%
- owner-occupied homes
Source: U.S. Census Bureau ACS 5-Year Estimates (2019–2023). Percentiles rank ZIP 20634 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 20634 (Great Mills, MD) rose +9.0% from 2023 to 2024. The all-transactions index moved from 207.9 in 2023 to 226.5 in 2024 (2000 = 100).
ZIP code 20634 is a mid-sized community (a standard USPS delivery area) in Great Mills, St. Mary's County, Maryland, home to 5,927 residents across 17.8 square miles, a density of 333 people per square mile, in the New York time zone.
ZIP 20634 skews affluent, with a median household income of $139,375 (22% above the average Maryland ZIP), while per-capita income is $61,800. Both reported hardship measures are comparatively low in absolute terms: poverty is 4.7% and unemployment is 1.3%. Home values sit below the statewide ZIP benchmark: the median is $342,300 (24% below the average Maryland ZIP), and median rent is $1,814; owner occupancy is 65.4%.
A solid share of residents have a four-year degree: 40.3% of adults hold a bachelor's degree or higher, the median age is 32, and the average commute is 24 minutes. The page also surfaces 10 ZIP codes within roughly 10 miles and 6 more in St. Mary's County, so 20634 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 20634
Top 5 sectors by establishment count in Great Mills, MD
Which industries have the most business establishments in ZIP 20634.
- Construction
Construction
11 establishments
- Retail trade
Retail trade
8 establishments
- Other services (except public administration)
Other services (except public administration)
8 establishments
- Administrative and support and waste management and remediation services
Administrative and support and waste management and remediation services
7 establishments
- Health care and social assistance
Health care and social assistance
6 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 20634, Great Mills, 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
5,927
Population
17.8
Area (sq mi)
333
People / sq mi
New York
Time Zone
standard
ZIP Type
Who lives in ZIP 20634?
32.0
Median Age
49.3%
Male
50.7%
Female
6.6%
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?
$139,375
Median Household Income
+22% vs state ZIP avg
$61,800
Per Capita Income
4.7%
Poverty Rate
1.3%
Unemployment Rate
23.6 min
Mean Commute Time
How ZIP 20634 ranks among Maryland ZIPs
Great Mills, 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)
$139,375 Top 26% higher than 74% 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
3,026housing units
3,026
Total Housing Units
2,694
Occupied Units
332
Vacant Units
2.62
Avg Household Size
Occupancy Type
$342,300
Median Home Value
-24% vs state ZIP avg
$1,814
Median Rent
1995
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
+9.0%
YoY Change (2024)
227
HPI Index (2000 = 100)
+127%
Total Change Since 2000
Home values in ZIP 20634 have increased 9.0% over the past year (2024). Since 2000, this ZIP has seen +127% cumulative appreciation.
| Year | Annual Change | HPI Index |
|---|---|---|
| 2020 | -3.2% | 172 |
| 2021 | +8.5% | 187 |
| 2022 | +18.5% | 221 |
| 2023 | -6.0% | 208 |
| 2024 | +9.0% | 227 |
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 48 business establishments in ZIP 20634, employing approximately 393 people with a combined annual payroll of $19,737,000.
48
Businesses
393
Employees
$19.7M
Annual Payroll
7
Industry Sectors
| Industry | Establishments | % of Total |
|---|---|---|
| Construction | 11 | 22.9% |
| Retail trade | 8 | 16.7% |
| Other services (except public administration) | 8 | 16.7% |
| Administrative and support and waste management and remediation services | 7 | 14.6% |
| Health care and social assistance | 6 | 12.5% |
| Real estate and rental and leasing | 5 | 10.4% |
| Professional, scientific, and technical services | 3 | 6.3% |
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 20634 vs 20620 →
ZIP 20634 vs its nearest neighbors, by population
Resident population of this ZIP and the closest reporting ZIP codes within ~10 miles.
- 20653
Lexington Park (20653)
24,481 residents
- 20619
California (20619)
10,503 residents
- 20634 5,927
Great Mills (20634)
5,927 residents
- 20688 1,828
Solomons (20688)
1,828 residents
- 20620 1,443
Callaway (20620)
1,443 residents
- 20692 1,051
Valley Lee (20692)
1,051 residents
- 20670 1,014
Patuxent River (20670)
1,014 residents
- 20674 830
Piney Point (20674)
830 residents
- 20690 740
Tall Timbers (20690)
740 residents
What this shows Among its immediate neighbors, ZIP 20634 ranks #3 by population - useful context the national average alone can't give.
ZIP 20634 vs its nearest neighbors, by median income
Median household income of this ZIP and the closest reporting ZIP codes within ~10 miles.
- 20630
Drayden (20630)
$233,411 median income
- 20692
Valley Lee (20692)
$201,250 median income
- 20674
Piney Point (20674)
$171,985 median income
- 20620
Callaway (20620)
$165,972 median income
- 20634
Great Mills (20634)
$139,375 median income
- 20690
Tall Timbers (20690)
$122,750 median income
- 20619
California (20619)
$119,432 median income
- 20653
Lexington Park (20653)
$103,048 median income
- 20688
Solomons (20688)
$102,950 median income
What this shows By household income, ZIP 20634 ranks #5 of 9 neighboring ZIPs, local affluence varies block to block, not just metro to metro.
| ZIP Code | City | Population | Distance |
|---|---|---|---|
| 20620 | Callaway, MD | 1,443 | 1.7 mi |
| 20692 | Valley Lee, MD | 1,051 | 4.1 mi |
| 20653 | Lexington Park, MD | 24,481 | 3.5 mi |
| 20667 | Park Hall, MD | 494 | 3.4 mi |
| 20619 | California, MD | 10,503 | 3.7 mi |
| 20630 | Drayden, MD | 348 | 5.7 mi |
| 20670 | Patuxent River, MD | 1,014 | 4.8 mi |
| 20674 | Piney Point, MD | 830 | 7.6 mi |
| 20690 | Tall Timbers, MD | 740 | 5.9 mi |
| 20688 | Solomons, MD | 1,828 | 6.5 mi |
Nationwide ZIPs with similar ACS profiles
Two Census-derived peer sets for ZIP 20634, 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 (5,927 here; floor ≥1,000).
Similar median household income
Nearest cross-state ZIPs by ACS median household income.
More ZIP Codes in St. Mary's County
Related Areas
Frequently Asked Questions
What county is ZIP code 20634 in?
ZIP code 20634 (Great Mills) is located in St. Mary's County, Maryland. St. Mary's County contains multiple ZIP codes, see the full list at /counties/st-marys-md.
What is the population of ZIP code 20634?
ZIP code 20634 in Great Mills, MD has a population of 5,927 according to the Census Bureau ACS 2023 estimates.
What is the median household income in ZIP 20634?
The median household income in ZIP 20634 is $139,375, which is 83% above the national average of $76,288.
What is the average home value in ZIP 20634?
The median home value in ZIP 20634 is $342,300, which is 23% above the national average of $278,155.
What is the demographic makeup of ZIP 20634?
The largest racial group in ZIP 20634 is White at 56.0%. Hispanic or Latino residents make up 8.5% of the population.
How many businesses are in ZIP code 20634?
ZIP code 20634 has 48 business establishments employing approximately 393 people, according to Census Bureau ZIP Code Business Patterns (ZBP) 2023 data.
What are the main industries in ZIP code 20634?
The top industries by establishment count in ZIP 20634 are: Construction (11), Retail trade (8), Other services (except public administration) (8). There are 7 industry sectors represented in total.
How have home values changed in ZIP code 20634?
According to the FHFA House Price Index, home values in ZIP 20634 increased by 9.0% in 2024. Since 2000, home values in this ZIP have appreciated by approximately 127%. 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 20634?
In ZIP code 20634, 59.3% of residents aged 25+ have a high school diploma or higher, and 40.3% 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 20634?
The mean commute time for workers in ZIP code 20634 is 23.6 minutes according to Census ACS data. The national average is roughly 26 minutes, so commuters here spend less time traveling to work than typical.
What percentage of residents own vs. rent in ZIP 20634?
In ZIP code 20634, approximately 65.4% of occupied housing units are owner-occupied and 34.6% are renter-occupied, based on Census ACS 2023 data.
What is the poverty rate in ZIP code 20634?
The poverty rate in ZIP code 20634 is 4.7% 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 20634's numbers, next.
- See how ZIP 20634 compares to a neighboring ZIP code on the same Census fields Compare this ZIP
- Check where Great Mills, 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.