FARGO, N.D. (March 26, 2009)--Thousands of people are taking part in an around-the-clock effort stacking sandbags to protect North Dakota's largest city from the rising Red River.

Fargo's mayor has asked workers and volunteers to add another foot to the height of the dikes, with the river expected to reach a record high crest on Saturday.

It has already topped 38 feet and the National Weather Service says it could reach 41 feet by then.

Officials are trying raise the level of the dikes to 43 feet.

Several nursing homes are evacuating residents ahead of the floodwaters, while people continue to leave homes south of Fargo.

Police are urging people with disabilities to consider leaving the city, and hospital officials are identifying patients that may need to be moved early.

Just to the north of neighboring Moorhead, Minn., officials say they need more volunteers to keep a low-lying township from being inundated.

A few homes have already flooded, and crews are trying to get the sandbags in place while it's still possible.

About 500 homes are threatened there.