Five years after Hurricane Katrina hit the Gulf Coast as one of the deadliest storms in U.S. history, Americans are celebrating the renewal of thousands of homes, businesses and livelihoods that have been restored since the disaster hit.

Cities like New Orleans were left destitute when Katrina slammed into the Mississippi-Louisiana coastline in 2005, killing nearly 2,000 people and displacing 300,000 others.

Today, the city has nearly 80 percent of its population back, and small business is booming.

After the storm, "We were a city that had no people in it," Ray Nagin, mayor of New Orleans when Katrina struck, told CNN.

"Now, we're a city that has over 80 percent of its population back. Lowest unemployment in the country. Construction everywhere. I think we're on our way to success," he said.

Many have returned with the help of faith-based organizations such as Church World Service (CWS) and the National Council of Churches who have led rebuilding projects in the area.

"If it weren't for the volunteers and agencies who assisted me, I don't know where I would be," said Gloria Mouton, 62, a retired government employee, whose home in New Orleans was among those repaired by CWS volunteers.

The United Methodist Church has deployed more than 250,000 volunteers in Mississippi and Louisiana since 2005, helping to rebuild nearly 12,000 homes.

"I never thought I would meet so many nice people this late in my life," said Leona Cousins, a 99-year-old Slidell, La. resident.

On Sunday, President Barack Obama visited New Orleans to spur residents towards continued progress and to assure them of the government's help.

"In the years that followed [Katrina], New Orleans could have remained a symbol of destruction and decay; of a storm that came and the inadequate response that followed," Obama said in a speech at Xavier University, a Catholic institution.

"It's not what happened across New Orleans and across the Gulf Coast. Instead this city has become a symbol of resilience and of community and of the fundamental responsibility that we have to one another," he added.

While focusing on the future, Obama did acknowledge that some parts of damaged cities have had little progress since the disaster, but promised that his administration would work with residents until the areas are restored.

"There are still too many vacant and overgrown lots. There are still too many students attending classes in trailers. There are still too many people unable to find work. And there are still too many New Orleanians, folks who haven't been able to come home," he said. "So while an incredible amount of progress has been made, on this fifth anniversary, I wanted to come here and tell the people of this city directly: My administration is going to stand with you - and fight alongside you - until the job is done. Until New Orleans is all the way back, all the way."

The president ended his speech with a reference the book of Job regarding the hope of renewal.

"When I came here four years ago, one thing I found striking was all the greenery that had begun to come back. And I was reminded of a passage from the book of Job: 'There is hope for a tree if it be cut down that it will sprout again, and that its tender branch will not cease,'" Obama said.

"The work ahead will not be easy, and there will be setbacks. There will be challenges along the way. But thanks to you, thanks to the great people of this great city, New Orleans is blossoming again," he continued. "Thank you, everybody. God bless you. And God bless the United States of America."