🇺🇸 United States ZIP Code

STANDARD

20851

Rockville

ZIP Code 20851 is a standard zip code serving Rockville, Rockville, Maryland (MD), in Montgomery County, United States. It has an estimated population of 14,191 with a median household income of $82,201. The area falls within the America/New_York timezone.

Median Household Income vs. National Average

Location

Country: 🇺🇸 United States
State / Province: Maryland (MD)
County: Montgomery
City: Rockville
Timezone: America/New_York

Coordinates

Latitude: 39.076300
Longitude: -77.123400

Geographic Details

Land Area: 2.37 mi²
Population Density: 5979.0 people per mi² (95th percentile)
Bounding Box: 39.094074°N, 39.062529°S, -77.105842°E, -77.141571°W

With 14,191 residents spread across 2.37 square miles, this area has a population density of 5979.0 people per square mile.

Demographics

14,191

Population

75th percentile

$82,201

Median Income

90th percentile

$332,300

Median Home Value

90th percentile

2.37 mi²

Land Area

The median household income in 20851 is $82,201, and the median home value is $332,300. This places the area in the top 25% nationally for household income.

Housing

5,042

Total Units

4,838

Occupied Units

96.0%

Occupancy Rate

Nearby ZIP Codes

Other zip codes in Rockville, MD.

20847

Rockville

20848

Rockville

20849

Rockville

20850

Rockville

20852

Rockville

20853

Rockville

20857

Rockville

Similar ZIP Codes in Maryland

ZIP codes with similar median household income in Maryland.

20659

Mechanicsville

$89,831

21014

Bel Air

$88,054

20886

Montgomery Village

$77,136

21090

Linthicum Heights

$71,938

20662

Nanjemoy

$85,069

20675

Pomfret

$89,934

20706

Lanham

$69,879

21017

Belcamp

$74,381

Frequently Asked Questions

What information is available for each ZIP code?

Each ZIP code page shows city, state, county, geographic coordinates, timezone, population, median household income, median home value, housing units, land area, population density, commute time, educational attainment, area codes, and ZIP code type (Standard, PO Box, or Unique).

What are the different types of ZIP codes?

There are three types of ZIP codes: Standard (residential and commercial delivery areas), PO Box (assigned to post office box sections), and Unique (assigned to a single high-volume address like a government agency or large company). Standard ZIP codes are the most common.

How often is ZIP code data updated?

ZIP code assignments are updated quarterly by the USPS. Demographic data comes from the US Census Bureau's American Community Survey (ACS), which releases new 5-year estimates annually. ZipFYI updates its data to reflect the latest available information.

What is population density and why does it matter?

Population density measures the number of people per square mile in a ZIP code area. It helps identify urban vs. rural areas, affects real estate values, impacts service availability, and is used in market analysis. Dense urban ZIP codes may have 50,000+ people per square mile.

How are ZIP code boundaries determined?

ZIP code boundaries are determined by the USPS based on mail delivery routes, not political or geographic boundaries. They follow carrier routes and may cross city, county, or even state lines. Boundaries can change when the USPS reorganizes delivery operations.

What does median household income tell me about a ZIP code?

Median household income is the middle value when all household incomes in a ZIP code are sorted. Half of households earn more and half earn less. It is a better indicator of typical earnings than average income, which can be skewed by very high or very low outliers.