This is a lofty claim about a map but these maps clearly show racially divided neighborhoods in American cities. What makes these maps so good?

1. Data and mapping software that allows for mapping at smaller levels. Instead of focusing on municipal boundaries, counties, or census tracts, we can now get at smaller units of analysis.

2. The colors on these maps are visually interesting. I don’t know how much they play around with that but having an eye-popping map doesn’t hurt.

3. Perhaps most important: there are clear patterns to map here. As documented clearly in American Apartheid twenty years ago, American communities are split on racial and ethnic lines.