Washington  - With record flooding in the Mississippi River basin, US President George Bush was travelling Thursday to inspect devastation as the storied river carried its flood crest toward Hannibal, the hometown of one of America's most beloved writers.

Thousands of volunteers were hefting sacks of sand to reinforce levees downstream from areas like Cedar Rapids, Iowa where waters were draining and recovery efforts have started. More than 20 levees have already broken, releasing some of the pressure into nearby fields and towns.

"The Mississippi doesn't play," said a grim Robert Betts, city manager of East St. Louis, where the flood is not expected to crest until Monday.

He was speaking in broadcast remarks as he surveyed waters that have already started to well up behind the levees there.

After days of heavy rain last week, experts are speaking of a record 100-year or even 500-year flood in the Mississippi River basin that drains the North American continent from Minnesota on the Canadian border south to New Orleans.

The more imminent target of the Mississippi's wrath is fabled Hannibal, Missouri, where the crest is expected to arrive on Friday.

That's the small town that writer Mark Twain turned into an icon of boyhood adventure and satire in the 19th century Middle West.

Under his birth name of Samuel Clemens, he worked as a riverboat pilot in the 1850s, where he gathered not only inspiration for characters and storyline but also for his pen name - Mark Twain - which was a measure of river depth called out to the pilot, which meant "mark two."

One of his boyhood homes has been turned into a museum that attracts droves of his fans to Hannibal every year. (dpa)