4.3.1. Animated Mapping

Below is the media file showing the temporal evolution of the ratio dividing the top percentile by the U.S. average personal income. More precisely, it consists in putting together all the annual maps of the ratio, and the juxtaposition of all maps chronologically creates an animated effect recorded in a video file. Ranging from 3.1 to 73.4 (in all years and states), the values of the inter-state ratio are displayed with 2 visual effects. The first one is a 3-dimensional projection that gives height to the state polygons, the height being equal to the state value of the ratio. The second is the partition of the values into 4 equal groups of colors, shading from light blue (low values) to dark blue (top values), breaking at the 3 quartile thresholds (Q25 = 6.6, Q50 = 8.4 and Q75 = 11).

Figure 4.17. Legend for the Video File

The animation file lasts about 1 minute and 30 seconds. Click here to play the video. For readers using the paper-version of this thesis, below is one map extracted from the video.

Figure 4.18. Inter-State Inequality in 1938

The evolution of the top income with respect to the national average is referred here as ‘inter-state convergence’, and can be summarized in a trend analysis.