This compact display packs quite a lot. We can easily identify which were the most popular states; and which candidate visited which states the most.
I noticed how they handled the legend. There is no explicit legend. The candidate names are spread around the map. The size legend is also missing, replaced by a short sentence explaining that size encodes the number of cities visited within the state. For a chart like this, having a precise size legend isn't that useful.
The next section presents the same data in a small-multiples layout. The heads are replaced by dots.
This allows more precise comparison of one candidate to another, and one location to another.
This display has one shortcoming. If you compare the left two maps above, those for Amy Klobuchar and Beto O'Rourke, it looks like they have visited roughly similar number of cities when in fact Beto went to 42 compared to 25. Reducing the size of the dots might work.
Click here to see the animation.
When repetition is done right, it doesn't feel like repetition.