Bank employee Trevor Beck sits on a pile of sandbags outside of his branch in LaGrange, Mo., where the Mississippi River crested and washed through the downtown last Tuesday. (Quincy Herald Whig, Jennifer Coombes/Associated Press)

Cresting flood waters moved down the Mississippi River north of St. Louis, Mo., Friday, inundating farmland and swamping small towns as people upstream began to clean up after the waterway's worst deluge in 15 years.

The flooding and severe weather are blamed for 24 deaths and the destruction of thousands of homes and buildings across five states in the U.S. Midwest.

Early damage estimates put the cost of repairs and rehabilitation of shattered lives and livelihoods at more than $3 billion US.

More than two dozen earthen levees meant to restrain the river were breached or topped by cresting waters, all of them in rural areas or small, riverside communities. Another 25 were at immediate risk of bursting or being overwhelmed, officials said.

In central Missouri's Lincoln County, 90 per cent of the levees that line the riverbanks were allowing water to flow into the surrounding countryside and threatening to completely deluge the town of Foley, emergency management spokesman Andy Binder said.

Foley resident Keith Aubuchon packed his belongings and abandoned his home Thursday, telling journalists he had also fled the catastrophic floods of 1993 and might not return when the waters retreated this time.

Not coming back: flood victim

"This is my second flood. I don't think there will be a third," Aubuchon said as he drove a pick-up truck loaded with a washing machine and other belongings away from his neighbourhood.

While the situation worsened in Lincoln County, it improved slightly elsewhere along the river after levee breaks upstream dissipated some of the record-setting crests as they moved south.

St. Louis is now expected to experience much lower crests than expected when the flood waters reach the city this weekend, forecasters said.

But upstream, areas behind broken levees were still struggling to contain the spreading waters, with towns several kilometres away from the Mississippi having to build barriers of sandbags to control the surge.

In Iowa, where residents are mopping up after the deluge in the cities of Cedar Rapids, Des Moines and Iowa City, President George W. Bush surveyed the flood's aftermath on Thursday and assured residents and rescuers that he is listening to their concerns.

"Obviously, to the extent we can help immediately, we will help," said Bush, still mindful of criticism that the government reacted slowly to Hurricane Katrina three years ago.

"You'll come back better," the president said. "Sometimes, it's hard to see it."

Billions available from Washington

Federal and state emergency management officials have said flood-ravaged communities can start tapping into more than $4 billion in new disaster-relief funding made available by Washington this week.

Iowa's crucial corn and soybean crops have also been extremely hard hit, with about two million hectares of farm fields waterlogged.

Corn prices stabilized Thursday after more than doubling in the past week, but the cost of compensating the state's hard-hit grain farmers could add billions to the overall cost of disaster relief, agriculture officials said.

With files from the Associated Press