A few months ago, we released a popular interactive map visualizing poverty by race from 1980 to 2010, which laid out in detail the intersection of poverty, race, and place in communities across the U.S. Since then, we’ve also received a few technical questions about how the map was made, and we’d like to share those so that others can create similar tools. Click here to read the complete how-to guide to creating an interactive dot density slider map.

Photo by Betsy Blaney/AP