Floodwaters from the bloated Mississippi River and its tributaries are having their biggest impact on those with the least. Levees have protected urban areas but not smaller, and usually poorer, communities from the Delta area down into Louisiana.
People used boats to navigate flooded streets as the crest rolled slowly downstream, bringing misery to poor, low-lying communities. Hundreds have left their homes in the Delta in the past several days as the water rose toward some of the highest levels on record.
The flood crest is expected to push all the way through the Delta by late next week.
"It's getting scary," said Rita Harris, 43, who lives in a tiny wooden house in the shadow of the levee in the Delta town of Rena Lara, population 500. "They won't let you go up there to look at the water."
Officials in the town, which has no local newspaper or TV stations, tried to reassure residents that they are doing what they can to shore up the levee and that they will warn people if they need to leave.
Mississippi Gov. Haley Barbour urged people to get out if they think there is even a chance their homes will flood. He said there is no reason to believe a levee on the Yazoo River would fail, but if it did, 107 feet of water would flow over small towns.
"More than anything else, save your life and don't put at risk other people who might have to come in and save your lives," he said.
The Mississippi Delta, with a population of about 465,000, is a leaf-shaped expanse of rich soil between the Mississippi and Yazoo Rivers, extending about 200 miles from Memphis, Tennessee to Vicksburg, Miss. Along the way are towns whose names are familiar to Civil War buffs, aficionados of the blues, and scholars of the civil rights era: Clarksdale, Greenwood, Greenville and Yazoo City.
While some farms in the cotton-, rice- and corn-growing Delta are prosperous, there is also grinding poverty. Nine of the 11 counties that touch the Mississippi River in Mississippi have poverty rates at least double the national average of 13.5 percent, according to the U.S. Census Bureau.
The governor said the state is asking local officials to get in touch with people who might have no electricity and phones and thus no way to get word of the flooding.
"It's a tiny number, but we have to find them," Barbour said.
Late Wednesday, President Barack Obama signed a disaster declaration for 14 counties in Mississippi because of the flooding. Housing and home repairs will be covered and low-interest loans to cover uninsured damage will be available.
In Greenville, Liz Jones, who is unemployed, lives on the second floor of a housing project and worries what might happen in the event of a levee break. She has no means of transportation.
"I got a baby and my mama. I don't know what we'd do about food and clothes and stuff," she said.
In Hollandale, one of the small rural towns in the Delta that the governor warned might flood if the levee breaks, 62-year-old nursing home worker Geraldine Jackson fretted about what to do if she and her husband have to leave their red-brick house, where pieces of the roof have broken off and the white trim is peeling.
"I have relatives, but all my relatives live in the Delta, and the water's going to get them too," she said. "I'm just real messed up."
In Natchez, the Mississippi on Wednesday broke the previous record of 58.04 feet set in 1937. It was broken 10 days before its expected crest there.
Thunderstorms, possibly severe, are expected Thursday night into Friday, which could bring another inch of rain into the area.
"Right now, the biggest concerns we have with the rains coming are with flash flooding," said Marty Pope, senior service hydrologist with the NWS, noting that water is backed up in tributaries.
Swollen by weeks of heavy rain and snowmelt, the Mississippi has been breaking high-water records that have stood since the 1920s and '30s. It is projected to crest at Vicksburg on May 19 and shatter the mark set there during the cataclysmic Great Flood of 1927. The crest is expected to reach New Orleans on May 23.
Even after the peak passes, water levels will remain high for weeks, and it could take months for flooded homes to dry out.
About 600,000 acres of cultivated row crops could flood, mainly winter wheat, corn, soybeans, cotton and rice, said Andy Prosser, spokesman with the Mississippi Department of Agriculture. Even if the levees hold, the state expects to lose $150 million to $200 million worth of crops, the governor said. Mississippi's catfish farmers could also be wiped out if the Yazoo floods their ponds and washes away their fish.
The state gambling industry is taking a hit: All 19 casinos along the river will be shut down by the end of the week, costing governments $12 million to $13 million in taxes per month, authorities said. That will put some 13,000 employees temporarily out of work.
In the Memphis area, where the Mississippi crested on Tuesday just inches short of the 1927 record, many of the flooded dwellings were mobile homes and one-story brick or wood buildings in low-lying, working-class neighborhoods unprotected by floodwalls or levees.
The damage in Memphis was estimated at more than $320 million as the serious flooding began, and an official tally won't be available until the waters recede.
Much farther downstream, Louisiana officials were awaiting an Army Corps of Engineers decision on whether to open the Morganza Floodway to take the pressure off the levees protecting Baton Rouge and, downstream, New Orleans and the many oil refineries in between.
Corps spokeswomen Rachel Rodi said daily inspections are being made on all levees along the Mississippi and Atchafalaya rivers, and so far no major problems have been spotted.
"It's nothing we haven't been able to handle," Rodi said.
Without the Morganza, New Orleans could be swamped by up to 25 feet of Mississippi River water, a new Corps map shows.
But there's also a downside — 2,500 people living across 3 million acres will get the water instead.
The Corps could start opening gates at the Morganza Floodway by Friday and Gov. Bobby Jindal told residents in the floodway to expect the water.
"You're looking at roughly 3 million acres that will be impacted, be underwater," Jindal said at a press conference.
Besides the 2,500 people and 2,000 structures inside the floodway, 22,500 other people and 11,000 structures will get some flooding, Jindal added.
"Everybody is just scared. They don't know what to do," said Ginny Higgins, a deputy sheriff in St. Martin Parish who was overseeing prisoners stuffing sandbags in stifling heat and humidity while clad in black and white striped jumpsuits.
Not releasing the water could put incredible stress on the levees protecting New Orleans, which is all too familiar with water given Hurricane Katrina in 2005.
And that stress danger will continue even after the Mississippi crests there around May 23.
"If the river begins to fall rapidly, we could have incidents where saturated levees slide into the river," , head of the Southeast Louisiana Flood Protection Authority-East, as saying.
On Monday, the Corps opened some gates at the Bonnet Carre Spillway, diverting water into Lake Pontchartrain.