Originally Posted by ChiSoxRox
Weighted population density is defined as the sum of the products of population (n) and density (ρ) for a tract, normalized to the entire population (N),
i.e. WPD = Σ (n*ρ) / N
Put another way, it is summing up the population of each tract (n) weighted by that tract's share (f) of the total population
WPD = Σ (n*f)
With the census tract numbering from Seattle in mind, I checked Los Angeles. 1031, 1732, 2309, ah the pattern doesn't hold. Wait, Beverly Hills is in the 7000s, Long Beach tracts are 57xx, and so on. What happens if I sum up the 1xxx and 2xxx tracts for Los Angeles County? Those seem to map to LA city limits! The total population in those tracts is 3,898,921. The city of Los Angeles is 3,898,747. Those tracts combined are less than 200 people away! A typical tract is 3k-4k people or so, so that cannot be a coincidence. I've checked the edges of LA city limits, and the 1xxx/2xxx tracts map to the city of Los Angeles! I've cracked the numbering code!
Edit - Turns out that depends on the city. For example, San Diego does not follow the self-partitioning pattern.
Weighted densities for cities proper
New York, NY…...65,299.0 ppsm
Jersey City, NJ…...36,846.2
San Francisco, CA…...33,572.5
Boston, MA…...27,437.4
Philadelphia, PA…...21,935.1
Chicago, IL.......21,235.2
Washington, DC…...20,642.9
Arlington, VA…...19,960.8
Los Angeles, CA…...17,294.3
Alexandria, VA…...15,708.3
Seattle, WA…...15,249.3
Baltimore, MD…...11,333.0
Milwaukee, WI…...9,506.5
Denver, CO…...8,889.4
New Orleans, LA…...7,189.8
St. Louis, MO…...6,834.8
Richmond, VA…...6,413.2
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