People in North Dakota in America are battling the worst flood waters for more than 100 years. Around 3,500 people have already been evacuated from their homes.
But not everyone is choosing to leave. Some people are building barriers around their homes to keep the water out. Which means they need bridges too.
Some people who chose not to leave have needed rescuing. This helicopter is hoisting a person in North Dakota to safety.
As well as the amount of water around, the freezing weather is creating problems as well. President Obama has been talking about plans to look after people affected.
The government has said it's getting ready to provide shelter for 30,000 people for around a week. If things get really bad, as many as 100,000 people may be homeless.
Sandbags are being used to build barriers to keep the flood waters at bay. Many, many people have been racing to fill enough of them to keep homes dry and safe.
Just making the sandbags isn't enough though. It's also important to get them to places they need to be.
The sandbags are being used to create dams or dykes that will keep the water out as long as it doesn't rise much higher.
The sandbags are also being used to make much bigger barriers to protect larger parts of towns.
And behind the barriers people are using water pumps to get rid of any water that does leak between the sandbags.