In Florida, officials closed a 35-mile stretch of Interstate 75 from the Georgia-Florida state line to Lake City, Fla., as well as a 40-mile stretch of I-10 Saturday morning. Georgia authorities closed the southbound lanes of I-75 for about 15 miles from Valdosta, Ga., to the state line because of the smoke.
"It's smoke and fog right now, but the fire is not far," said Bill Hamilton of the joint fire information center.
Several accidents have occurred on the two highways and that area roads are at near-zero visibility, emergency management officials said. A multi-car accident occurred on the interchange between the two highways northwest of Lake City, a Florida Highway Patrol spokesman said. It was unclear if there were any injuries.
Residents, both young and old, have been breathing in ash-filled air for three days, reports CBS News correspondent Kelly Cobiella. People with breathing problems are being told to stay inside.
"I think we've been fairly fortunate that we have had relatively few people present with exacerbations of their problems because of smoke," said Dr. Stanley Janasiewicz who directs Emergency Medical Services for Columbia County.
The fire, which started in the middle of the Okefenokee National Wildlife Refuge, took just six days to grow larger than a separate wildfire that has burned 124,000 acres of Georgia forest and swampland in more than three weeks.
The fire is about five miles from homes on the edge of Lake City, Fla. It hasn't moved much in 24 hours, but it's only about 10 percent contained and all it would take is one windy day to get the fire going again, Cobiella reports.
Residents evacuated late Thursday from about 600 homes in northern Columbia County, Fla., were still unable to return home Saturday morning, said Jim Harrell, of the Florida Division of Forestry.
In Georgia, the fire posed a potential threat to the town of Fargo, where 380 people live about eight miles west of the Okefenokee Swamp. Occupants of about 15 homes were urged to leave as a precaution because of the smoke and ash.
Meanwhile in California, residents have started returning to Catalina Island after firefighters and favorable weather halted a wildfire's advance into the island's most populated area.
Nearly 4,000 evacuated residents began heading back to inspect their homes and apartments and reopen businesses that largely cater to tourists.
"I thought it would be a melted ball of plastic," said Jim Gilligan, who reached his workplace, Dave Zeller Construction, on a golf cart. He was pleasantly surprised to find the building still standing — especially with charred ground 30 feet from the door.
Tourists were barred from Catalina Island until at least Monday — past the Mother's Day weekend that had been expected to jump-start the summer season.
An average of 1 million tourists a year pump $96 million annually into the economy of the island about 20 miles off the Southern California coast, a vacation paradise with snorkeling, scuba diving, golf and hiking in an ecologically diverse terrain.
Wayne Griffin, president and CEO of the Catalina Island Chamber of Commerce, estimated that the ban on visitors would cost Avalon, the island's only significant town, a half-million dollars in just a few days.
"Until some of these things stabilize, we're probably not a good place for visitors," he said. "It's a small price to pay when you consider what we saved."
The Catalina blaze started Thursday afternoon and burned about 4,200 acres — about 6 of the island's 76 squares miles. Containment was estimated at 35 percent.
Avalon Fire Chief Steven Hoefs said the cause of the fire remained under investigation but it appeared to have started as contractors worked on antennas at a radio station in the island's interior.
Only one home and six industrial businesses burned and no one was seriously injured.
Environmentalists said it was too early to tell how the Catalina blaze affected the island's ecosystem, home to rare animal and plant life, including the Catalina Island fox.
But four bald eagle chicks that hatched earlier this year without human help were unharmed, said Bob Rhein, a spokesman for the Catalina Island Conservancy, which owns most of the island. The birds are a milestone in the reintroduction of the species, which was wiped out on the island decades ago by chemical contamination.
To the north, some evacuation orders were lifted in northeastern Minnesota, where a wilderness wildfire had blackened about 85 square miles of forest. However, an evacuation order was expanded across the border in Canada because of concerns about shifting wind, said Ministry of Natural Resources spokeswoman Leona Tarini.
Dozens of houses and cabins have been burned, and about 300 people had checked in at an evacuation center.
Fire crews hoped to take advantage of a break in the weather Saturday, with lighter wind and a 40 percent change of rain on Sunday.
Crews prepared for a planned burnout Saturday on the west side of the finger of fire that had reached out over Gunflint Lake, to keep the line of fire from spreading and to protect structures between Gunflint Lake and Loon Lake.
"Hopefully, it (the fire) won't have anything left to burn," said Mark Van Every, a spokesman for the firefighting effort.