Ten years ago, Hurricane Katrina devastated the city of New Orleans and its environs. It was one of the costliest natural disasters to strike the United States. But as we’ll explain, Katrina wasn’t a “natural disaster” but instead the accumulated product of environmental and social inequities spanning two hundred-plus years. Beginning with Katrina and New Orleans, we’ll look at historical linkages between public health, extreme weather and geologic events, chemical exposure and climate change using examples from New York City, Chicago, Seattle, and Baltimore. We’ll conclude by comparing United States cities to urban locations in the global South. As we’ll argue, urban environments have long been shaped by histories of social and environmental disparities. The consequences of this history have already yielded immense costs in the past—and they will present further challenges in a new era of global climate change.