Crews, composed of state, local and federal firefighting agencies, worked overnight battling the fire in Wisconsin's Bayfield and Douglas counties.
No injuries had been reported, but some homes and cabins were among the dozens of structures burned down, the Duluth News Tribune reported. Some area residents were evacuated to Red Cross centers away from the blaze, officials said.
Several utility poles also were burned, downing electrical and telephone lines in some areas, officials said.
Wisconsin Department of Natural Resources representatives said the fire was about 85 percent contained Wednesday morning, but that the windy conditions could help rekindle it.
The DNR said it is the largest fire in the state in many years.