Cool graphs of trends in income inequality within states

Below are 50 little graphs showing the 90th percentile and 10th percentile in income, within each state, for the past forty years. The patterns are pretty striking: the high end has increased pretty consistently in almost all the states, and the low end increased a lot in poor states, especially for the first half of the series. I don’t really know what more to say about this–we made the graphs because we are trying to understand the differences between rich and poor states in the past 20 years, and what has made them into “blue” and “red” states–but the graphs are full of interesting patterns. Incomes are inflation-adjusted and presented on a logarithmic scale (with a common scale for all the graphs), and the states are ordered from poorest to richest.

OK, here’s the picture:


And here are the trends since 1981, plotted vs. avg income within states:

In poor states, the poor have been doing better; in rich states, the rich have been doing better.

Income inequality between states

All states have been getting richer over the decades (as measured by average real incomes). Up until about 1980, income inequality between states decreased, then since then it’s increased slightly (which is consistent with the above scatterplots). Here’s the key picture:


Further discussion is here.

7 thoughts on “Cool graphs of trends in income inequality within states

  1. The grid around those fifty states is overwhelmingly black. Could it be grayed down a little, and/or the data curves be given a bright, non-black color of their own?

  2. This is a fascinating set of graphs.

    It's not surprising to see a scatterplot showing that in poor states the poor have a higher growth rate; this could be a regression effect.

    It's very surprising to see that the rich do better in rich states; that seems counter to regression effect tendencies.

  3. Derek,

    Good point; I'll redo them.


    The numbers are very stable over time, so the regression-effect phenomenon doesn't seem so relevant here.

  4. It seems that the 10th percentile of income is approaching a similar value in all states. Possibly this reflects the poor moving to richer states, and industry moving to states with lower labour costs. The end result is similar demand and hence cost for low skilled labour.

    The rich doing better is what makes a state rich. If the rich did worse it would squeeze down the range of incomes, and they would be a poor state.

  5. Could you do the State-comparison curve for deciles (and centiles if you have the data)?
    I'm always having issues with National & regional averages, that generally fail to represent the local, therefore visible relative widening or coming together.

  6. I have to confess, I wish you would provide a bit more standard and clearer explanations for what we are looking at. In the little state graphs, is the y-axis dollars? Is each axis equal? I.e., is the middle of each little graph $X,000? Thanks. (Sorry to be crabby; these are fascinating…I think…)

  7. Bertil,

    I think my historical data on the deciles only go back to 1963.


    Details are in the book. The y-axis is in log inflation-adjusted dollars (ranging from $2000 to $125000).

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