The United States this week marks 20 years since Hurricane Katrina cut a swath of destruction from South Florida to the Gulf Coast, ultimately overwhelming New Orleans on 29 August 2005 after peaking in the Gulf as a Category 5 storm with 175-mile-per-hour winds and a central pressure of 902 millibars. Katrina’s storm surge—measured at up to 28 feet—breached levees and left about 80 percent of New Orleans under water. Federal agencies now put the storm’s U.S. death toll at roughly 1,392, while other tallies reach 1,800. More than one million people were displaced and economic losses topped $125 billion, making Katrina the costliest U.S. natural disaster at the time. The catastrophe permanently altered the city’s social fabric. The destruction of the Orleans Parish school system cleared the way for the nation’s first all-charter public-school district, a transformation that educators credit with expanding choice but that remains the subject of ongoing equity debates. Former students and teachers say the storm also propelled many of them into careers in education and public service. Katrina accelerated changes in meteorology and emergency management. Forecasters cite the storm’s rapid Gulf intensification and subsequent levee failures as catalysts for today’s sharper computer models, real-time graphics and more forceful risk communication. While technology has improved, meteorologists warn that warmer oceans linked to climate change raise the odds of Katrina-scale events and underscore the need for continued investment in coastal resilience.