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Seattle, Washington

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Census Data for Seattle ...

Population ...

The most recent Census Estimate<1> was for 2019 and it gave Seattle a population of 753,291 people.

The last Decennial Census<2> was in 2010, which gave Seattle a population of 608,660 people.

The city of Seattle is located in King County. The 2010 Census gave King County; a population of 1,931,249 people. This means that Seattle had 31.52% of the county's total population, making it King's most populous community.

At the same time, Washington had a population of 6,724,540 people, meaning that Seattle had 9.05% of the total population of Washington - making it the state's most populous community.

Area ...

The 2010 Census shows that the sampling area for Seattle has a total area of 142.7 square miles [369.5 km²]. Of this total, 83.9 square miles [217.4 km²] is land, with the balance (41.16%) being water (58.7 square miles [152.1 km²]).

King County has a land area of 2,115 square miles [5,479.3 km²]. At 83.9 square miles [217.4 km²], Seattle has 3.97% of the county's total land area.

  • Continue Reading ...
    • When the Census Bureau conducts a census for a city like Seattle, they draw a boundary around the area in which they are going to conduct their count - this defines the sampling area (usually a polygon). The shape of the sampling area can be quite complex and it's important to keep in mind that the boundaries of the sampling area may or may not match the recognized boundaries of the city.
    • Things like population, area and housing for Seattle reflect the sampling area. Since the shape of the sampling area and the actual boundaries of Seattle might be different, it's best to check with the U.S. Census Bureau to resolve any difference between the two.
    • Not only does the sampling area define boundaries, it also has a GPS location (latitude & longitude) that indicates a point within the sampling area (usually the center of the polygon, known as the centroid). At the time of the 2010 Census, the sampling area was located at:
    • Lat:   47° 37' 13"   (or 47.62°)
    • Lon:   -122° 21' 3"   (or -122.35°)
    • More information on this topic and the changes between the 2000 Census and the 2010 Census can be found in the section for our Census-to-Census Observations ... (see below).

Housing Units ...

At the time of the 2010 Census, Seattle had 308,516 Housing Units<3> and with its population of 608,660 people, this averages 1.97 people per Housing Unit.

  • Continue Reading ...
    • The 2010 Census shows Seattle had a land area of 83.9 square miles [217.4 km²]. This translates to 2,162 Housing Units per square mile [835 housing units/km²].
    • From the Census of 2000: Seattle had 270,524 Housing Units, a population of 563,374 people and a land area of 83.9 square miles [217.2 km²]. This gives a density of 2.08 people per Housing Unit and 1,897 Housing Units per square mile [732 housing units/km²].
    • Note: Repeating the caution above (under Population Density), be aware that when comparing Housing Units between the 2010 and the 2000 Census, there were changes in the sampling area for Seattle and you need to be careful when comparing results between the censuses. More information about these differences can be found in the section called Census-to-Census Observations ... (see below).

King County ...

Seattle is located in King County<4> and is the County Seat for King County.

The county had a population of 1,931,249 people at the 2010 Census. With it's population of 608,660 people, Seattle represented 31.52% of the county's total.

In addition, where the city of Seattle has a population density of 4,266 people per square mile [1,647 people/km²], King County averages 912 people per square mile [352.5 people/km²].

For more information, please visit our Census Page for King County.

Census-to-Census Observations ...

Introduction ...

When the Census Bureau takes a census count (or enumeration) for Seattle, they start by specifying the boundaries of the area to be counted. This area (or sampling area) is a polygon and its shape can be quite complex - it may or may not match the geographical boundaries of Seattle. It's important to note that from one Census to the next, the shape and location of the polygon can change.

  • Continue Reading ...
    • Although we don't have specific information about the shape of the polygon for Seattle or how it changed has over time, there is some information that can give us some hints. For example, since the shape of the sampling area is directly related to the shape of the polygon, any change to area probably indicates a new shape for the polygon.
    • If you need precision or details about the methodology of the Census, you should visit the U.S. Census Bureau for a definitive answer.

Location ...

While generally coinciding with the GPS location (latitude/longitude) of Seattle, the latitude and longitude given by the Census Bureau actually indicates the GPS location of the polygon for Seattle.

  • Continue Reading ...
    • For the 2010 Census, the location was given as:
    • Lat:   47.620499°   (or 47°37'13" N)
    • Lon:   -122.350876°   (or -122°21'3" W)
    • For the 2000 Census, the location given was:
    • Lat:   47.626353°   (or 47°37'34" N)
    • Lon:   -122.333144°   (or -122°19'59" W)
    • The difference indicates that the U.S. Census Bureau moved the location of the polygon for the 2010 Census 4,851 feet to the southwest<5> of the location that was used in the 2000 Census.
    • The U.S. Geological Survey (USGS) and the U.S. Board on Geographic Names (BGN) have assigned a unique GNIS identifier (#2411856) to Seattle. This identifier also marks a GPS point on the map, and that point lies within the boundaries of Seattle. The GNIS point has been mapped to the latitude/longitude:
    • Lat:   47.620486°   (or 47°37'13" N)
    • Lon:   -122.351030°   (or -122°21'3" W)
    • The GPS location given for the 2010 Census lies 38.14 feet to the east<6> of the point given by the GNIS for Seattle. For more information about this and the relationship of the various Federal Codes, please visit our Misc Page for Seattle.

Miscellaneous Information for Seattle ...

The Federal government has assigned various identifying codes to each community, county and state. At one time or another, the US Census Bureau has used one (or more) of the following identifiers when referring to either King County or the city of Seattle:

  • The GNIS Codes ...
    • The current system of identification is called the Geographic Names Information System (GNIS). The following GNIS codes relate to Seattle:
    • GNIS ID for Seattle: 2411856
    • GNIS ID for King County: 1531933
    • GNIS ID for State of Washington: 1779804
  • The FIPS Codes ...
  • Misc. Census Codes ...
    • Seattle is located in Census Region #4 (the West Region) and Division #9 (the Pacific Division).
  • The US Postal Service ZIP Code ...
    • While some people have used a ZIP code to identify a community, the purpose of the ZIP code was to make mail delivery more efficient by grouping addresses together. Although the ZIP Code doesn't specifically identify a city like Seattle, it does identify addresses that are in (or near) Seattle. It's important to remember that the boundaries of a ZIP Code can be changed, re-assigned or overlapped with other ZIP Codes.
    • The ZIP code for Seattle:98101<7>
  • Census ZCTA Codes ...
    • The US Census Bureau created statistical entities that they call ZIP Code Tabulation Areas (ZCTAs) and these ZCTAs are frequently confused with the ZIP codes that come from the US Postal Service (USPS).
    • ZCTAs were first created for the 2000 Census and at that time, they were based upon the USPS ZIP codes. While largely covering the same areas, the boundaries of a ZCTA do not necessarily match the boundaries of a postal ZIP code with the same number. For example, while a postal ZIP code can cross a county or state line, a Census ZCTA can not. They should be treated as separate entities with no correlation between them.

For more information about the various Federal identification codes, please visit our Misc Page for Seattle.

Other Roadside Stops ...

The Communities of Washington

About King County

About Washington

Off-the-Road Links ...

The official website for Seattle:

The official website for King County:

The official website for State of Washington:

The official website of the U.S. Census Bureau

The official website of the U.S. Board on Geographic Names (BGN)

The official website of the U.S. Geological Survey (USGS)

Footnotes ...

<1>Every year, the US Census Bureau creates a population estimate for the preceeding year. Keep in mind that this value is an estimate and not an actual count. The most recent Census estimate is for the year 2019.
<2>Every 10 years (eg- 1990, 2000, 2010), the US Census Bureau conducts a Constitutionally-mandated count (or enumeration) of people living within the United States. This count is called a Decennial Census. The last Decennial Census was the 2010 Census, with the next one planned for 2020.
<3>A Housing Unit is a broad term for those places where people live (whether occupied or temporarily vacant), such as a house, an apartment, a mobile home, or an area that is considered as a separate living quarter. Separate living quarters (consisting of one or more rooms) are considered to be those places where people live, sleep and eat separately from others and that have access to the outside (either directly or by a shared hallway).
<4>If you're interested in how the shape of Washington's counties, including King, have changed over time, we recommend the Atlas of Historical County Boundaries.
<5>The calculated bearing (or angle) to the 2010 Census location is 116 degrees and a distance of 4,851 feet.
<6>The calculated bearing (or angle) to the GNIS point is 277 degrees and a distance of 38.14 feet.
<7>When looking for a ZIP Code, whether Seattle or elsewhere, it's always best to check the website of the United States Postal Service (USPS).






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This page was last modified: 27 Apr 2022