Hurricane Katrina lashing the coast at Gulfport, Mississippi, USA, on 29th August 2005. Katrina was a category four hurricane when it hit the Gulf of Mexico coast of the USA. It left a huge trail of damage, most notably in New Orleans. There, failure of the levee flood defenses meant that around 80% of the low-lying port city was flooded. Thousands lost their lives. The evacuation of the entire city of 1.3 million people was ordered on 8th September. Katrina is thought to be the most deadly and costly natural disaster in US history.