Floodwaters along the Mississippi River moved south Wednesday, as some areas in the southern U.S. braced for record flooding in the coming days.

Thousands of residents in several states have evacuated their homes along the river and its tributaries as flooding — triggered by rain and melting snow — has reached levels not seen in decades.

A National Weather Service spokesman told VOA that forecasters are especially watching the city of Vicksburg, Mississippi, where the water level is expected to hit 17.5 meters next week, exceeding a record set during the Great Mississippi Flood of 1927.

On Wednesday, U.S. President Barack Obama declared a major disaster in Mississippi and ordered federal aid to supplement state and local recovery efforts in areas affected by the flooding.

Throughout the region, authorities worked Wednesday to reinforce levees, while farmers built their own in an effort to protect their crops.

The river crested Tuesday in Memphis, the largest city in the state of Tennessee. The crest reached 14.6 meters, just short of its all-time record more than 70 years ago.

Mr. Obama declared a major disaster in Tennessee on Monday, ordering federal aid to help state and local recovery efforts in the area. The state also was struck by severe storms and tornadoes last month.

The president has signed emergency or disaster declarations for other states hit by flooding and bad weather, including Louisiana, Iowa, Kentucky and Missouri.

The Mississippi River is North America’s largest river system. It spans more than 3,700 kilometers from the northern United States to the Gulf of Mexico.