In cities well inland, like Fayetteville, North Carolina, the floodwaters are continuing to rise, even as the main remnants of the storm moved over the Mid-Atlantic states and into New England on Tuesday.
At least 16 rivers remained at a major flood stage, with three others due to crest in the coming days in North Carolina, according to forecasts.
Florence, which made landfall on Friday as a Category 1 hurricane before it was downgraded, has already killed at least 36 people, including 27 in North Carolina and eight in SC.
"Most importantly, we give thanks to the incredible first responders, including sheriffs, police officers, firefighters, our great Cajun Navy", Trump said.
Officials said more than 1,100 roads are closed, 255 of those primary roads.
Parts of two major interstate highways were still under water Tuesday.
Hurricane Florence bypassed South Florida, but we haven't forgotten the need for relief after Hurricanes Irma and Maria impacted us and our neighbors in Puerto Rico.
Property damage from the storm is expected to come to $17 billion to $22 billion, the risk management firm Moody's Analytics said.
The North Carolina Department of Agriculture and Consumer Services projected the animal death toll after emergency workers and veterinarians spent days in the field assessing losses at farms following the storm.
Much of Columbus County, where Fair Bluff is located, was under water, according to Steve Abbott of the North Carolina Department of Transportation, with most roads closed and "driving not advised".
Also scheduled to attend Tuesday's briefing are the chief of the National Guard Bureau and the adjutant general of SC.
"We've never had it at those levels before, so we don't really know what the impact will be just yet", he said.
Trump, who has been criticized for the federal government's handling of Hurricane Maria in Puerto Rico a year ago, told officials at a briefing before going to the Marine Corps Air Station Cherry Point in Havelock, North Carolina, "We're going to be there 100 percent".
Photos from the site provided to AP by Cape Fear River Watch, an environmental advocacy group, show cascades of gray-colored water spilling from at least two breaches at the landfill and flowing toward Sutton Lake, the plant's former cooling pond which is now used for public recreation, including fishing and boating.
Todd Tremain needed tarps to cover up spots where Florence's winds ripped shingles off his roof.