How methods shift perception of population growth
The Seattle Times recently reported on 2010 census data by tabulating the “fastest growing” cities in Washington State and writing a feature about Snoqualmie, on the top of the list at 396% growth since 2000. As with many media outlets, they ranked areas based on percentage growth, not absolute numbers of people. In the table below are the 10 fastest growing cities, ranked on percentage growth as printed in the Seattle Times.
10 Fastest Growing Washington Cities Ranked by Percent Growth
Footnote: Percentages based on initial 2000 census data. Seattle Time table based on adjusted 2000 census data.
Note that most of these towns are rather small. It is easy to grow by 200% if you start out at a population of 2,000. You may not have heard of many of these towns. But if you looked them up on a map, you would see that most of these towns are on the urban fringes of the Seattle-Tacoma metro area. The takeaway could easily be that urban sprawl and small town living are very popular. Policies such as growth management have failed, and most people have chosen with their feet to move to the exurbs.
But what if we ranked “fastest growing” cities by the number of people that moved in? In the table below the top 10 cities in Washington state for 2000 to 2010 population increase are listed.
10 Fastest Growing Washington Cities Ranked by Total Growth
This list is very different from the first list. The three cities that appear in both lists are highlighted. Larger cities may add a lot of new residents, but their percentage growth is less than small towns because they started from a larger base. Yet, one more modification is needed to accurately compare growth between cities. Some of the cities in this list, such as Marysville, increased in population mostly due to annexations of adjacent previously populated areas. Washington State keeps records of populations of annexed areas, so I subtracted these populations from the population increase reported in the 2010 Census. In the table below the 10 fastest growing cities in Washington State are ranked based on population increase, excluding annexations.
10 Fastest Growing Washington Cities Ranked by Total Growth, Annexations Excluded
Now the list of the fastest growing cities is similar to a list of the largest cities in the state. Only one city, Issaquah, an outer Seattle suburb, remains from the original list. The City of Seattle tops the list as fastest growing. Tacoma is notably absent, but large cities in other parts of the state grew strongly. Two of the three tri-cities are listed, Kennewick and Pasco. So are Spokane and Vancouver, the Portland metro’s second city. In the Seattle metro area, the fastest growing suburbs are established (and affordable) middle-ring suburbs such as Renton, Kent and Auburn. The takeaway from this list is different from the first list: most people moved to large towns and suburbs; and the most of all moved to Seattle, the fastest growing city in the state.
Please keep in mind, when developing stats, do you want to calculate magnitude of growth, or magnitude of growth compared to the initial base? If the former, look at absolute numbers not percentages.
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