Teaching Resources Depository
Exploring the US Census
Eugene Turner, California State University, Northridge
5 -- Describing Relative Locations of Populations
- Select one
of the tracts in the Burbank or Glendale cities. Compute the distance between
this tract and all others in the city.
Sort the tracts by distance and select those tracts that are within one
mile of your central tract. Sum the populations to get the total population
within your ring distance. What proportion of the city's population is within
your service area?
- Repeat the
same procedure for selected U.S. counties. Select a county with a large
central city and determine the population within 25 miles of your central
The center of gravity gives a sense of the center of a distribution of a population.
If many members are located in one area, the center will be pulled toward
subgroups of the larger population you can gain some appreciation of differences
in the distributions of the subgroups by comparing their centers to one another
and to that of the total population.
- Compute the
center of gravity of the U.S. population by averaging the latitudes weighted
by county population and longitudes weighted by county population for each
of the counties in 1980. Repeat this process for 1990. How far and in which
direction did the population shift?
- Compute the
population center of gravity for states such as California, Nevada, Florida,
Illinois, and Utah. In what states are the population centers near the spatial
centers of the states?