Data Rep, ah! I redid the sketch with Jer’s help and after class, I understand a bit more about the data— it’s the mention of the word “elections” in the NYT archive since 1986.
What a mystery! Now the “periodicity” of the data makes more sense— as you can see in the way the colors lay out through the grid. The colors correspond to the numbers we were given— so the higher the number, the brighter the color on the HSB range.