This dissertation investigates the practices and processes that manage flood risk in New Orleans. The focus of the investigation is the production of New Orleans’ place on the deltaic floodplain of the Mississippi River and the city’s new Digital Flood Insurance Rate Map. A combination of low-lying geography and a deep history of flooding means redrawing New Orleans’ Flood Map is a matter of significant consequence for equity, the economy, and the environment. Flood maps are the backbone and bane of the Federal Emergency Management Agency’s (FEMA) administration of the trillion-dollar National Flood Insurance Program (NFIP). Although essential to the NFIP, updating the United States’ 22,500 flood maps has become burdensome. With the NFIP as the backdrop, I ask how FEMA could redraw New Orleans’ Flood Map in such a way that more than half of the below-sea-level city was redefined as suddenly free from flood risk. To answer this question, I draw on ten months of ethnographic field research in New Orleans, including observational studies and transect walks, and over 50 semi-structured interviews with public officials and experts. I also draw on scholarship from the fields of science and technology studies, environmental history, and urban studies. My research reveals the production of a new flood map is laden with tension and uncertainty. Led by FEMA, experts synthesize constituent technoscientific knowledge practices into a flood map. In turn, contrasting values and beliefs shape how public officials and residents read a flood map. However, a flood map represents only a snapshot of social, environmental, technoscientific relations frozen in space and time. While the lines on a flood map are fixed in place, sometimes for decades, the dynamic landscapes that it represents are in constant flux. In this way, flood maps and the NFIP can be understood as instruments that perform a crucial but compromised role in rationalizing the uncertainty of littoral futures across the United States.