Triggered by a La Niña weather pattern, the unsually strong storms delivered punishing rainfall to the upper Midwest and tornadoes to Arkansas and drought-stricken portions of Texas.
Midwestern farmers expecting a windfall this year from rising food prices have delayed planting crops in many areas because of the turbulent weather.
Farmers in the 18 biggest corn-producing states had planted just 9% of their acreage by Sunday, compared with 46% on the same date last year, according to U.S. Agriculture Department.
In Kentucky, the Ohio River swelled well out of its banks. "It's like an ocean," said Kevin Trunnell, a farmer near Utica, Ky., surveying the flood waters about 12 miles south of the river.
Mr. Trunnell's land is mostly on high ground, but the heavy rains have kept him from planting corn and other crops.
Governors in Missouri, Arkansas and Kentucky declared states of emergency after the damage and in anticipation of more flooding.
With rains continuing, the National Weather Service is predicting the Mississippi River will crest at 60 feet next month in Natchez, Miss., surpassing the record of 56.6 feet set in 1927—a monster flood that left 26,000 square miles inundated, according to the Army Corps. More than 200 people died and some 600,000 people were displaced.
Out of that disaster came the Flood Control Act of 1928, which led to the nation's first comprehensive flood-control program.
The Army Corps said Tuesday it would decide later whether to blow up a levee at Birds Point, Mo., to reduce the pressure on levees across the Mississippi River at Cairo, Ill. The plan, approved in the 1920s but used only once since, would send a stream of water over some 130,000 acres of prime Missouri farmland, eventually flowing 35 miles before returning to the Mississippi at New Madrid, Mo.
Missouri officials moved in federal court in Cape Girardeau, Mo., Tuesday to block the plan, just as the Corps was seeking approval to move forward from the multistate Mississippi River Commission. The Corps said it would continue to discuss the plan Wednesday, while moving equipment into place in case the plan goes through.
Clay Shelby, who farms corn and soybeans on 800 acres that would be flooded if the levee is blown up, said the water wouldn't just sit on his land.
"The current is what we're afraid of," he said. "It will scour the ground, our roads and all the improvements that we've made to those farms."
In Arkansas, where nine people were killed, four of the victims died when a tornado swept through the small town of Vilonia in the central part of the state, just north of Little Rock. The storm cell ripped trees out of the ground by their roots and smashed homes into scattered heaps of debris.
"It's pretty bad," said Capt. Matt Rice of the Faulkner County Sheriff's Department. "We've got a lot of houses that were totally destroyed. Some were blown completely apart."
In southeastern Missouri, Poplar Bluff residents began evacuating after the levee protecting the town of 17,000 breached Monday. About 250 people have checked into a shelter in the Black River Coliseum, said Cheryl Klueppel, executive director with a regional chapter of the American Red Cross.
The town is dealing with the second breach of the levee since 2008. "What I'm hearing from a lot of folks is it's deju vu. We're doing this all over again," she said.
Tony Hill of the Corps said the federal government was willing to share the cost of repairing the levee to federal standards after the 2008 disaster, but the local levee district couldn't come up with its share of the funds.
As a result, the levee received an "unacceptable" rating in 2008 and therefore won't qualify for federal help to repair the breach this time.
The flood waters have left many people's lives in Poplar Bluff in disarray yet again. Marsha Bostick, 63 years old, who helps sell the local newspaper, said her house was inundated in 2008. She eventually moved into another house that had survived the 2008 flood.
"I'm tired of moving. I'm going to just rebuild," she said at the shelter. "I'm not worried about the furniture, stuff like that, you know. It's the memories. You can't get that back."