Many people have been protesting in America as they are angry about something called the Dakota Access Pipeline.
Newsround looks at exactly what this pipeline is, why it's being built and why it has caused disagreements.
What is the Dakota pipeline?
The Dakota pipeline is a special pipe, which will be used to carry oil from the US state of North Dakota to another state called Illinois.
Once the oil gets to Illinois via the pipeline, it can be taken to special places called refineries, where oil is cleaned to make it ready to use.
Plans to develop the pipeline began in 2014. This week, the company behind the pipeline said it is getting ready to be used.
Until recently, there was a section of it still left to be built because the authorities were exploring other routes that this bit of the pipeline could take.
This was so that it wasn't built near a certain area called Standing Rock (find out more about why below).
But as soon as Donald Trump - who supports the pipeline - became the new US president at the beginning of 2017, builders were given the go-ahead to finish it off.
The finished line is 1,200 miles long and cost £2.8 billion to build.
It will be able to carry about 470,000 barrels of oil in a single day, running underneath both land and water, through four different US states.
Why do people think it's a good idea?
Supporters of the pipeline say it is the safest way to transport oil to the rest of the country.
Not only that, but they say it is cheaper than carrying barrels of oil by train.
They also said that building it would create jobs for people.
Why are people against it?
Thousands of people have protested against the pipeline being built, including Native American tribes who live at an area called Standing Rock.
They are not happy as the final section of the pipeline crosses near here, and they think it could harm sacred burial sites and contaminate drinking water.
They also say that the government didn't speak to them before building it, which they should have done.
Many people have travelled to the Standing Rock area to protest with them, including Native Americans from other areas.
Other protestors do not agree with the pipeline because they do not think that fossil fuels - like oil - are good for the environment.
What happens now?
The protestors have said that they will not give up protecting their land, and so the protests continue.
They have also taken their argument to the courts to try to stop the pipeline from starting to be used, but we will have to wait to see what will happen.
On Monday, the company behind the pipeline said they are preparing to put the pipeline into full service.