OAKVILLE, Iowa — Even before the Iowa River used this town as a shortcut to the Mississippi, there wasn’t much here: A post office, a convenience store, a tavern and a little restaurant.

The largest employer was a pork-and-grain producer called TriOak Foods. The company’s towering grain elevator was the tallest structure for miles around.

Then the floodwaters soaking much of the Midwest turned their force on the region’s small communities — most with skylines that consist only of a water tower and maybe a couple of church steeples.

As the rivers rise, these modest towns survive because neighbor helps neighbor, and the people reinforcing the levees are business owners, farmers, and fellow church members who have lived there for years.

“My house is past help. So we’re trying to save everybody else’s,” Bethany Frank said as she helped fill sandbags in a church parking lot in Oakville, about 40 miles southwest of Davenport. Her home on the outskirts of town was flooded up to the roof.

Yesterday, Iowans assessed their losses from flooding that inundated Des Moines and Iowa City. But small towns up and down the Mississippi still awaited the worst of the flooding. Some rivers were not expected to crest until today.

Storms and flooding across six states this month have killed 24 people, injured 148, and caused more than $1.5 billion in estimated damage in Iowa alone — a figure that’s likely to increase as river levels climb in Missouri and Illinois.

Federal officials predicted as many as 30 levees could overflow this week, leaving industrial and agricultural areas vulnerable but sparing major residential centers. So far this week, 20 levees have overflowed.

At least 10 levees have been topped in Illinois and Missouri in recent days, including two south of tiny Gulfport, Ill., that threatened to swamp 30,000 acres of farmland near the evacuated town of Meyer, Ill.

Governor Blunt of Missouri sent 600 members of the National Guard to the northeastern part of the state, plus another 100 to the St. Louis area to help towns further downstream. In Illinois, 1,100 Illinois National Guard troops have been sent to help flooded communities.

“My property is right on this street. I’ve got a lot to lose,” said Tony Dye, whose home in Canton, Mo., stands beneath the levee and well below the river’s expected crest. The river was projected to crest at Canton today at nearly 14 feet above flood stage.

Even if population hubs are spared, some fear entire communities may be lost forever, possibly wiping off the map names such as Columbus Junction, Fredonia, Palo, and New Hartford.

About 70% of Iowa towns have populations of less than 1,000. Just over half of those places have fewer than 500 inhabitants.

Elsewhere in the state, parts of downtown Burlington remained flooded yesterday, but sandbagging efforts had stopped and officials said they were confident levees would hold. The Great River Bridge at Burlington was still closed due to high water.

In Cedar Rapids, officials allowed more people into damaged homes and businesses. Residents were being urged to conserve water because the water system had only half its normal supply.

South of Iowa City, the town of Columbus Junction, population 2,000, suffered a major blow because it’s below the confluence of the Iowa and Cedars rivers. The medical center, pharmacy, day-care, senior center, a hotel, and a dozen other businesses were under about 10 feet of water after a levee broke Saturday.