Why is a wall at the border so important to Donald Trump?
Building a wall was one of Donald Trump's key promises when he was campaigning to become president.
It was an idea that divided the country, but won Donald Trump many supporters.
And now, two years into his presidency, he wants to deliver on that promise.
A wall at the border between the US and Mexico would be designed to prevent people from entering the United States illegally.
Currently, there is a total of 650 miles of barrier along the border which is 1,900 miles long.
However, Donald Trump believes this is not enough to turn away people attempting to cross the border.
In a televised speech, he stated, "All Americans are hurt by uncontrolled, illegal migration."
"We are out of space to hold them and we have no way to promptly return them back home to their country," he continued.
President Trump wants to build a 1,000 mile wall made out of steel to prevent people from crossing the US-Mexico border.
He believes the rest of the terrain along the border should be enough to prevent people from attempting to cross.
But building a wall of this size is going to cost a lot of money.
How is he hoping to build the wall?
Originally he suggested that Mexico should pay for the wall - but it was soon very clear that the Mexican government would not pay.
Now, President Trump is appealing to his own government and therefore, to US taxpayers, to pay for the wall.
He estimates that he would need $5.6 billion (the equivalent to £4.4 million) to build a steel barrier across the border.
So you see how mean Trump is being he does not even care about the Mexican in the last bit it made me feel very sorry for the Mexicans he nearly wanted the Mexicans to pay for the wall and you have no clue how collosal that wall is or how much the Mexicans will have to pay he is the one that came up ith the idea that is very bad.