The US is set to mark five years since Hurricane Katrina hit the Gulf coast, killing more than 1,800 people and leaving New Orleans under water.
US President Barack Obama will visit New Orleans, where sombre ceremonies are planned, including a tolling of the bells at St Louis Cathedral.
Louisiana residents held a symbolic burial for victims on Saturday.
The storm, which hit land on 29 August 2005, displaced hundreds of thousands of people.
Mr Obama will make a speech at Xavier University - which, like much of New Orleans, was flooded when the levees protecting the city were breached by flood tides.
The president is expected to reassure survivors who have returned to the city that he is committed to completing the rebuilding of New Orleans.
'We're survivors'
A march and "healing ceremony" have also been scheduled in a district of the city where many houses still stand vacant.
The houses still have a circle painted on them in 2005 to indicate that they had been searched, and whether bodies were in them, the Associated Press reports.
"I'm tired of the anniversaries," 77-year-old Barbara Washington told AP, explaining that she had been living in the suburbs since Katrina struck.
"I miss my home every day. I feel lost. But I also know we are getting back. We're survivors."
During a symbolic burying of victims of Katrina in Chalmette, Louisiana, residents were invited to write "farewell Katrina" messages and place them in a coffin, which was then buried.
"You made us stronger and made us realise what was important in life. One day we will feel better," read one note.
Gregory Aymond, Archbishop of New Orleans, led the ceremony, telling the congregation: "Where was God five years ago on this day? Here, weeping with us, and trying to console us in the midst of a natural tragedy."
