People were afraid it would be like Hurricane Katrina, which did much damage in 2005, especially to the city of New Orleans, Louisiana. But Gustav never got as strong as Katrina. It grew to a Category 3 storm, and Katrina was a Category 5.
There was damage and flooding, as you can see in the photo taken in New Orleans. The city was evacuated (everyone was ordered to leave). The National Guard was called to help. This photo was taken by a soldier, Sergeant Michael L. Owens.
Other places also got ready for the storm. In all, over 2 million people left southern Louisiana.
Many people in Gulfport, Mississippi, also evacuated. But their city was not badly damaged. Some roads were flooded and some power lines were knocked down.
The U.S. government says this time, it got ready before the storm hit. Dave Paulison, head of the Federal Emergency Management Agency, says that also, "a lot of people understood what they had to do. "
The National Hurricane Center says Gustav is now just a tropical depression. But it's not over yet. There is still a tornado watch for parts of Louisiana and Mississippi. There is also a flood watch for those two states and southwest Alabama.