The Red River in the midwestern state of North Dakota has risen to levels never seen in recorded history and is threatening to flood the city of Fargo.
The swollen river broke a 112-year-old record Friday, when it rose above the previous high of just over 12 meters.
The river is expected to crest at nearly 13 meters on Saturday, very close to the top of the city's main dike.
The powerful floodwaters caused a significant leak in a dike early Friday, prompting authorities to evacuate 150 homes in downtown Fargo.
Since then, the city of 92,000 people has called for further evacuations.
Residents, National Guard troops and emergency workers are working non-stop in subfreezing weather to construct makeshift dikes with sandbags in an effort to hold the rising waters.
Fargo's mayor Dennis Walaker says residents do not want to give up without a fight.
The flat terrain of the Red River Valley means floodwaters could cover a wide area.
U.S. forecasters say it is unclear where the floodwaters would go since the Red River has never been known to rise to this level.
The National Weather Service says it expects the floodwaters to stay above record levels for another week.
Some information for this report was provided by AP.