Problem, research strategy, and findings : In this study I investigate whether zoning has traditionally protected communities of color from the dangers of heavy commercial and industrial use to the extent that it has protected White communities. I evaluate whether upzonings-changes from less intensive uses to more intensive heavy commercial and industrial uses-disproportionately occurred in African-American and low-income neighborhoods in Durham (NC) from 1945 to 2014, and I evaluate the comparative impact of downzonings. I use the contemporary demographics of the census tracts where these rezonings occurred and qualitative evidence from public hearings, plans, and other relevant primary materials. I find that before 1985, the pattern of rezonings in Durham had negative implications for African-American areas in particular. Environmental justice efforts in the 1980s, followed by gentrification, caused the city's planners and local elected officials to change course. Takeaway for practice : Planners have an ethical obligation to promote equity, and their ability to do so depends on understanding sources of social injustice. In Durham, race historically played a role in upzonings and downzonings involving heavy commercial and industrial uses. The city also demonstrates that planners and local elected officials can successfully intervene to end disparities in zoning practice across communities of different racial characteristics. Assessing past zoning practices in other cities may reveal similar records of bias and help planners to present cases for corrective action.