Because environmental justice is inherently a conversation about geography (i.e., where in our states, cities, and towns are environmental burdens most concentrated), maps represent a natural tool for articulating and addressing environmental justice issues. In many ways, using mapping as a way to identify cumulative impacts is the natural outgrowth of what Charles Lee and his colleagues started in 1987 with Toxic Wastes and Race in the United States, one of the first publications to put data behind the pattern of disparate impacts that many in this country had witnessed for years. By distilling lessons learned from two of the most developed mapping tools in the country—California Environmental Protection Agency’s CalEnviroScreen and the U.S. Environmental Protection Agency’s EJ Screen—Charles Lee’s article paves the way for future mapping efforts.