CAIRO, Ill. (AP) - More rain fell Monday as the Army Corps of Engineers pumped liquid explosives into a southeastern Missouri levee and weighed whether to blast it open to ease inland flooding and spare an Illinois town where most residents already have been forced to flee from a rising river.

The prepping of the Birds Point levee pressed on as the already swollen Mississippi and Ohio rivers absorbed as much as 5 inches of rain that pummeled parts of the region Sunday night through Monday morning, straining levees including the 64-foot flood wall protecting Cairo, Ill., from the swelling Ohio. The tiny town sits across the Mississippi River from Missouri, near where the two rivers meet.

Even more rain was expected Monday - as much as nearly 2 inches at Cairo - before letting up Tuesday afternoon.

The corps said Monday on its Facebook page it had made no decision on whether to intentionally breach the levee in Missouri's Mississippi County, noting it expected to discuss the matter publicly later that morning.

Missouri officials opposed the possible breach, saying it could inundate 130,000 acres of farmland and crush the region's economy and environment by possibly covering the land under feet of sand and silt and rendering it useless. But their efforts to block a blast failed to sway a federal judge, an appeals court and U.S. Supreme Court Justice Samuel Alito, who without elaborating Sunday rejected the state's latest and perhaps final bid to stop the corps from sacrificing the levee.

The ruling by Alito, who handles emergency requests from Missouri and various other Midwest states, came the same day all but 20 to 30 families in 2,800-resident Cairo were ordered out of the city and away from the Ohio, which eclipsed its 74-year-old record height was expected to rise further.

As Illinois National Guard troops went door to door with local law officers to enforce the mayor's "mandatory" evacuation order, those who were allowed to stay - a courtesy extended only to adults - did so at their own peril, signing waivers acknowledging they understood the risk.

A few hours later, Maj. Gen. Michael Walsh, the corps officer who ultimately will decide the levee's fate, ordered crews to move barges to the Missouri side of the river and begin loading pipes embedded in the levee with a sludge-like explosive in anticipation of blowing up a 2-mile section just downriver from Cairo.

Walsh said it would take 20 hours to get the pipes filled - time he would spend observing the rivers' rise and the rain, which continued pounding the region early Monday.

The Ohio, as of Monday morning, had risen to 61.05 feet at Cairo - eclipsing the 1937 record there of 59.5 feet. The river was expected to crest Wednesday at 61.5 feet and stay there for at least into Friday, raising the corps' concerns about the strain the water was putting on the floodwall in Cairo and other cities. Cairo's floodwall can handle water up to 64 feet.

Given the record water levels, "this is a dramatic, once or twice in a lifetime kind of occurrence" for the region, Missouri Gov. Jay Nixon said after touring the levee Sunday with Walsh. "We understand the general and his team have difficult decisions to make."

Cairo and the rest of Alexander County can ill afford major flooding. The area's non-seasonally adjusted unemployment rate stood at about 12 percent in March, 3 percent higher than the state average. Several of the county's sheriff's cruisers were repossessed in recent years because it hadn't paid its bills.

Cairo served as Gen. Ulysses S. Grant's headquarters early in the Civil War and became a hub of commerce thanks to rails and the rivers, growing to 15,200 residents by the 1920s. But air travel undermined its geographic importance, and employers and many residents left the city after a race riot in 1967.

On Sunday, the city looked apocalyptic, with police cars the only traffic on its streets. Prisoners filled sandbags in an auto-parts business' parking lot. Saturated ground had given way under some streets, in one case leaving a crater about 8 feet deep near another stretch of buckled road.