🇺🇸 United States ZIP Code

STANDARD

98611

Castle Rock

ZIP Code 98611 is a standard zip code serving Castle Rock, Castle Rock, Washington (WA), in Cowlitz County, United States. It has an estimated population of 9,133 with a median household income of $57,532. The area falls within the America/Los_Angeles timezone.

Median Household Income vs. National Average

Location

Country: 🇺🇸 United States
State / Province: Washington (WA)
County: Cowlitz
City: Castle Rock
Timezone: America/Los_Angeles

Coordinates

Latitude: 46.278300
Longitude: -122.913900

Geographic Details

Land Area: 124.59 mi²
Water Area: 1.71 mi²
Population Density: 73.0 people per mi² (45th percentile)
Bounding Box: 46.387465°N, 46.199409°S, -122.687491°E, -123.044223°W

With 9,133 residents spread across 124.59 square miles, this area has a population density of 73.0 people per square mile.

Demographics

9,133

Population

65th percentile

$57,532

Median Income

70th percentile

$203,600

Median Home Value

75th percentile

124.59 mi²

Land Area

The median household income in 98611 is $57,532, and the median home value is $203,600.

Housing

3,760

Total Units

3,528

Occupied Units

93.8%

Occupancy Rate

Similar ZIP Codes in Washington

ZIP codes with similar median household income in Washington.

98030

Kent

$51,446

98674

Woodland

$64,572

98570

Onalaska

$51,106

98168

Seattle

$49,233

98557

Mccleary

$51,690

98467

University Place

$61,386

98087

Lynnwood

$63,639

98664

Vancouver

$53,290

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.