Residents of Mississippi and Louisiana are bracing for possible floods as the Mississippi River is expected to rise next week to levels not seen since 1927. On Tuesday, forecasters said the river had begun cresting in Memphis, Tennessee, rising to nearly 48 feet.

The National Weather Service said the river measured 13.84 feet above flood stage as of Tuesday morning. In Memphis, that's the highest level the river has been since 1937.

CNN reported:

The Mississippi is the highest it's been at Memphis since 1937, when it crested at 48.7 feet -- 14.7 feet above flood stage. That flood killed 500 people and inundated 20 million acres of land, said Col. Vernie Reichling, the Corps of Engineers Memphis District commander.

So far, the levees protecting the area have only shown minor weaknesses, which workers have been able to control, he said.

"We design these levees for the worst possible case and them we add two to three feet of freeboard. So what you're seeing today is these levees and floodwalls performing as designed," he said.

Authorities in Memphis believe the worst may have already passed. "I think we feel fairly confident from the modeling that the water has done what it is going to do," said Bob Nations, director of the Office of Preparedness in Shelby County, Tennessee. "But I say that with a lot of caution in mind because we don't know that for certain."

The river has already unleashed major floods in low-lying areas. Voice of America reported: "Thousands of residents in several states have evacuated their homes along the Mississippi River as flooding - triggered by rain and melting snow - has reached levels not seen in decades."

The river crest will continue to head south towards Mississippi and Louisiana.

ABC News reported:

The river will continue to press against Memphis levees for at least the next few days, officials said. The Mississippi there has swollen to six times its average width.

Further south, residents of Vidalia, La., have been warned to start working on an evacuation plan. City officials have already evacuated the local hospital. Vidalia is directly located across the river from Natchez, Miss.

Officials said the river is expected to crest at a record level there on May 21. Businesses owners and residents have been preparing for the worst by filling sandbags.

Louisiana Governor Bobby Jindal urged residents to prepare for possible floods now. "People with property that would flood if the spillway is opened should not dally,” he said. “My advice to our people is not to wait, to get prepared now.”

President Obama on Monday declared a major disaster in Tennessee, which opens the way for federal aid to help the state in its recovery efforts. Obama also signed emergency or disaster declarations for other states affected by bad weather or floods, including Iowa, Kentucky, Louisiana, Mississippi and Missouri.