Based on barometric readings, the hurricane is the third most powerful to ever hit the U.S. mainland.
More than 2 feet of rain has fallen in places as the hurricane-turned-tropical storm parks itself over the two states. Forecasters say another 1½ feet could fall by the end of the weekend.
The Category 4 hurricane is packing winds up to 130 mph and water that could wreak havoc over a wide stretch of the eastern United States later this week.
The storm is expected to quickly weaken as it moves toward Arkansas. It did not reach hurricane status.
Forecasters say heavy rainfall and flash flooding are the biggest threats posed by Subtropical Storm Alberto, the first named storm of 2018.
While news outlets focus on the threat to the southern U.S., environmentalist Bill McKibben underlines the danger in the Caribbean.