Karen Clark & Co., which produces models for catastrophes, said that if 1989's Hurricane Hugo had hit SC in 2012, just 23 years later, insurance losses would have more than doubled to $10 billion when development and inflation are factored in.
Forecasters said parts of North Carolina could get 20 inches (50 centimetres) of rain, if not more, with as much as 10 inches (25 centimetres) elsewhere in the state and in Virginia, parts of Maryland and Washington, D.C.
Rain measured in feet is "looking likely", he said.
"There's just certain times of year when you just don't want to put waste on fields", said Mike Yoder, an associate director and coordinator for emergency-response programs at North Carolina State University Extension.
Trump has declared states of emergency for North and SC ahead of the Category 4 hurricane, which frees up help from federal agencies. "Please be prepared, be careful and be SAFE!"
President Trump met with federal disaster officials at the White House on Tuesday.
Typically local governments in North Carolina make the call on evacuations.
SC lifted mandatory evacuation orders for three coastal counties as the storm's path became more certain.
The menacing Category 4 storm packed winds of 130 miles (215 kilometers) per hour over the Atlantic.
In the six decades since, many thousands of people have moved to the coast.
"Monster" Hurricane Florence aims to drench Carolinas
Predictions now have the storm stalling and making a slight southward turn after it makes landfall. Henry McMaster has ordered evacuations in counties along the state's coast, including Charleston.
Meteorologist Jon Cash tells CBN News that wherever Florence comes ashore, that area will likely be devastated, facing destructive winds and days of torrential rain.
"Florence is expected to produce total rainfall accumulations of 15 to 20 inches with isolated maximum to 30 inches near Florence's track over portions of North Carolina, Virginia, and northern SC through Saturday", says the National Hurricane Center.
If Florence stalls rain and flooding could be our biggest issues. "This rainfall could produce catastrophic flash flooding and significant river flooding".
Once the storm makes landfall, the threats are far from over.
Florence's projected path includes half a dozen nuclear power plants, pits holding coal-ash and other industrial waste, and numerous hog farms that store animal waste in huge lagoons.
Duke coach David Cutcliffe says the team will leave Durham on Thursday instead of its typical Friday departure because it's "our best opportunity to get out".
"We are in a very deadly and important game of chess with Hurricane Florence", he said.
A warm ocean gives hurricanes their fuel, and Florence is moving over an area with water temperatures nearing 85 degrees (30 Celsius), hurricane specialist Eric Blake wrote.
NHC forecasts showed the effects of Florence would be widely felt, with tropical storm-force winds extending almost 300 miles across three states. Information gathered Tuesday by a hurricane-hunting aircraft suggests it will intensify again as it nears the coast, approaching the 157 miles per hour (253 kph) threshold for a worst-case Category 5 scenario. But the storm is expected to strengthen again over the next day or so. That would mean more flooding rains across a large part of the U.S. South, expanding the damage, according to Chuck Watson, a disaster modeler with Enki Research in Savannah, Georgia. Even if you've ridden out storms before, this one is different. It goes without saying that SC farmers don't need yet another major weather challenge this year after having so many weather disasters in the past. "We are expecting more wind than we had with Hugo and more water than we had with Matthew".