Officials told the Los Angeles Times that the hurricane-related death toll has grown to to seven, with five in Louisiana and two in Mississippi.
The slow-moving storm is pushing into drought-stricken areas in the Midwest with its center now well into Missouri. NBC News meteorologists report the heavy rains stretched for miles early Saturday east of Illinois amid reports of tornadoes and high winds.
Flash-flood warnings are now cropping up across the Midwest as Isaac makes its way north into the Mississippi and Ohio River Valleys this weekend, according to the National Weather Service.
Jenny Bland, 50, of Indianapolis, told NBC that she waited in line more than 90 minutes so she could pick up sand bags for her family and elderly neighbors to guard against flood waters.
"People are taking this very seriously," Bland said.
Areas of Arkansas saw up to 8.5 inches where there were several flash flood watches and warnings on Friday.
By Saturday, there were signs of improvement across Louisiana. Officials told the Los Angeles Times they hoped to restore power to all but 10% of households in the state, down from 26% late Friday. And about 4,370 people stayed overnight in shelters Friday across the state, about 1,700 fewer than Thursday.
In New Orleans, Gadeaon Fentessa, an employee of the Magnolia Discount Gas Station in the Carrollton neighborhood, told AP that up to 50 drivers an hour were pulling in hoping they would be able to get gas but his station had no power. Stations that did have power to pump had long lines.
Presidential candidate Mitt Romney visited Louisiana on Friday and President Obama has a visit scheduled for Monday.
"I'm here to learn and obviously to draw some attention to what's going on here," Romney told Louisiana Governor Bobby Jindal when they met along a highway to discuss challenges facing the stricken area. "So that people around the country know that people down here need help," reports the Associated Press.
Romney toured Lafitte, a fishing village south of New Orleans, where he saw soaked homes, roads covered with brown water and debris-littered neighborhoods, reports AP.
Isaac dumped as much as 16 inches of rain in some areas as it made its way across the U.S. About 500 people had to be rescued by boat or high-water vehicles.