Officials have confirmed a 16th death attributed to Florence.
The South Carolina Department of Public Safety says a pickup truck was traveling east on a road near Gilbert, South Carolina, around 6 a.m. Sunday when it drove into standing water on the roadway.
Officials say the driver, identified as 30-year-old Rhonda R. Hartley, lost control and went off the side of the road, hitting a tree. The driver died at the scene.
Officials in South Carolina are warning about dangerous flash flooding throughout the state as rains from the remnants of Hurricane Florence continue.
The driver's name wasn't immediately released.
Flood waters fueled by Florence's heavy rains have submerged instruments used by the federal government to monitor river levels in North Carolina, causing at least two of them to stop working.
The U.S. Geological Survey said Sunday that a gauge on the Cape Fear River near Chinquapin stopped transmitting after hitting its limit of 24.2 feet (7.38 meters). A gauge on the Trent River in Trenton, North Carolina, stopped working when water levels hit 21.5 feet (6.55 meters). Major flood stages at those sites occur when the rivers reach 15 or 16 feet (4.6 or 4.9 meters).
Supervisory hydrologist Douglas A. Walters says more gauges are likely to become submerged and stop working. The gauges are normally installed well above the heights floodwaters are expected to reach. USGS crews have been working in the field over the weekend to raise some gauges even higher.
Tropical Depression Florence has picked up speed as it continues dumping heavy rains over the Carolinas.
The National Hurricane Center says Florence is moving north at 14 mph (22 kph) - a brisk pace compared to its sluggish crawl across the region since Thursday, when it barely topped speeds at which most humans can walk.
Florence's top sustained wind speeds held at 35 mph (55 kph). By 5 p.m. Sunday, Florence was centered about 25 miles (40 kilometers) south-southeast of Greenville, South Carolina, and about 60 miles south-southeast of Asheville, North Carolina.
Forecasters say Florence is still expected to produce excessive rainfall as it turns from the Carolinas over the Mid-Atlantic and southern New England early this week.
Motorists who would ordinarily travel through North Carolina are still being asked to stay out because of poor road conditions in the aftermath of Florence.
Bill Holmes, a state spokesman, said Sunday the message is: "Please don't come through here if you can avoid it."
Authorities say flooding is widespread, conditions are changing constantly and the roads need to be kept clear for first responders. High water has led to closures on Interstates 40 and 95, two major arteries.
The North Carolina Department of Transportation posted a map online of what it acknowledged was an "extremely long detour" through Tennessee and Georgia for travelers heading south on Interstate 95. It also warned that GPS systems are routing users into areas the department doesn't recommend for travel.
A map with real-time road conditions is available online .