The Mississippi River flowed into the most poverty-stricken parts of the United States yesterday, leaving some low-lying Memphis neighborhoods inundated, but the city's high levees protected much of the rest.

Over the past week floodwaters along the rain-swollen river and its backed-up tributaries have washed away crops, forced many to seek higher ground and closed some of the dockside casinos that are vital to the region's economy.

But the worst is yet to come, with the crest expected over the next few days.

The damage in Memphis was estimated at more than US$320 million as the serious flooding began, and an official tally won't be available until the waters recede.

To the south, there were no early figures on the devastation, but with hundreds of homes already damaged, "we're going to have a lot more when the water gets to where it's never been before," said Greg Flynn, a spokesman for the Mississippi emergency management agency.

Across the region, federal officials anxiously checked and reinforced the levees, some of which could be put to their sternest test ever. In northwestern Mississippi, crews have been using dirt and sand to make a levees higher, said Charlie Tindall, attorney for the Mississippi Levee Board.

About 16 kilometers north of Vicksburg, contractors lined one side of a backwater levee with big sheets of plastic to keep it from eroding if floodwaters flow over it as feared - something that has never happened to the levee since it was built in the 1970s.

In Vicksburg, the river was projected to peak on Saturday just above the record set during the cataclysmic Great Flood of 1927. Widespread flooding was expected along the Yazoo River, a tributary that is backed up because of the bloated Mississippi. Rolling Fork, home of the bluesman Muddy Waters, was also in danger of getting inundated.

Farmers built homemade levees to protect their corn, cotton, wheat and soybean crops, but many believed the crops would be lost entirely. More than 3,900 square kilometers of farmland in Arkansas have been swamped over the past few weeks, and the economic impact will be more than US$500 million, according to the state's Farm Bureau.

The Mississippi crested in Memphis at nearly 14.6 meters, just short of its all-time record of 14.6 meters.