Biden received an aerial tour of the damage in Tallahassee, Florida, on Thursday where the hurricane made landfall as a category four storm last week.
Speaking later in Ray City, Georgia, Biden told residents: “I see you, I hear you, I grieve with you, and I promise you we have your back.
“We’re going to stay until you’re restored.”
The president has approved federal disaster assistance for survivors in Florida, Georgia, North Carolina, South Carolina and Virginia.
Tens of thousands of people have no running water in North Carolina, which has seen some of the most severe impacts of the storm, particularly in the mountainous area of Asheville.
“I feel like I just survived the apocalypse,” Nicole Rojas, a Vilas, North Carolina, resident told the BBC.
An elderly couple, Jerry and Marcia Savage, died in bed when a tree fell on their home in South Carolina, their grandson told the Associated Press news agency. He said they were found hugging one another.
Hundreds of roads remain closed, hampering efforts to send aid to hard-hit communities.
Private citizens have been helping distribute aid in a variety of ways, including by mule and privately owned helicopters.
Mountain Mule Packer Ranch has deployed a team of mules to help carry thousands of supplies into remote communities.
The “sure-footed” pack animals are familiar with backcountry trails, and can travel on broken asphalt in ways that vehicles cannot, says mule-packer Michele Toberer.
“They are perfectly prepared for the conditions of the mountains,” she says.
So far, the team of nine mules has delivered hundreds of pounds of insulin, baby formula, nappies, canned food, cleaning supplies, and animal feed, she tells BBC News, adding that the biggest challenge they’ve faced so far is from the deep mud left behind by the floods.
