MOORHEAD, Minn.  Residents of about 2,700 homes were urged to leave this riverside city on Friday, as the Red River surpassed its highest level in history. And as volunteers here noted wearily, the river was likely to bloat further on Saturday.

“This has all been kind of an oddball deal,” said George Tokheim, 98, as he sat in his wheelchair inside a school gymnasium that has been turned into a shelter, pondering the airboat ride that took him from his home on Friday. “Just last night, we all figured we would tough it out. But today, everyone seemed to have changed their minds completely.”

There was no end in sight for those who were advised to leave their homes, including hundreds more in threatened neighborhoods across the river in Fargo, N.D., and in smaller communities to the south where the houses now poke out of the icy waters like islands.

The Red River is expected to crest on Saturday in Fargo, but it is then expected to sit swollen for days. Coast Guard workers in boats and helicopters have already rescued more than 80 people in the region. Who knew, Mr. Tokheim said, when he might leave his cot-filled gymnasium?