TRUMP: 'Why was there the Civil War? Why could that one not have been worked out?'

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Donald Trump.

President Donald Trump asked why the Civil War happened in an interview with journalist Salena Zito set to air Monday on Sirius XM.

"People don't realize, you know, the Civil War, if you think about it, why," the president said. "People don't ask that question, but why was there the Civil War?"

"Why could that one not have been worked out?" he continued.

Trump made the comments after going on a lengthy riff about President Andrew Jackson, a past president Trump believes was similar to himself in his populist views and bombastic campaigning.

"I mean, had Andrew Jackson been a little later, you wouldn't have had the Civil War," Trump said of the slave-owning president. "He was a very tough person, but he had a big heart. He was really angry that he saw what was happening with regard to the Civil War. He said 'there's no reason for this.'"

Jackson, who was president from 1829 to 1837, died in 1845, 16 years before the outbreak of the Civil War.

The Civil War broke out after years of tensions between the northern and southern states, namely over the issue of slavery and of whether western territories being added to the union would enter as "slave" or "free" states, which had a significant effect on the makeup of Congress. In total, 11 southern states seceded from the US and formed the Confederate States of America, and the war between the Confederacy and the Union was, to this day, the bloodiest in US history. It eventually led to the abolition of slavery in the US, freeing millions of slaves in the South.

Earlier in the interview, Trump mentioned that people told him he was "most like Andrew Jackson with his campaign."

"And I said, 'when was Andrew Jackson?'" Trump said. "It was 1828. That's a long time ago."

He said Jackson "had a very mean and nasty campaign" and "unfortunately it continues."

"His wife died," Trump said. "They destroyed his wife and she died. He was a swashbuckler, but when his wife died you know he visited her grave everyday? I visited her grave actually because I was in Tennessee."

Listen to Trump's comments: