What we don't know, though, is the most important number: How high it will be? Trump's been vague about this and has a recent applause-grabbing habit of randomly increasing the height. So we did our best to figure out how big this thing was going to be.
One of the first mentions of specifics on Trump's wall came in a speech last August.
"So you take precast plank," Trump said. "It comes 30 feet long, 40 feet long, 50 feet long. You see the highways where they can span 50, 60 feet, even longer than that, right? And do you a beautiful nice precast plank with beautiful everything. Just perfect."
He added: "I want it to be so beautiful because maybe someday they'll call it the Trump Wall."
Happy to call it that now! So, The Trump Wall will use precast planks. Engineer Ali Rhuzkan looked at that idea last September and based his designs on a 30-foot wall. Which would look something like this (with Trump for scale).
By October, though, the wall had moved to the higher end of Trump's original spectrum -- perhaps up to 50 feet high.
Which would look like this.
That's a big difference. Rhuzkan's estimate was that a 30-foot wall would use more than three times the total concrete in the Hoover Dam. With this extra 20 feet of concrete, we’re up to at least four Hoovers.
In an interview on MSNBC the day of the New Hampshire primary, Trump scaled the wall back. It would be "a real wall," he said -- probably 35 to 40 feet.
A few minutes later in February
When MSNBC's Tamron Hall pointed out that Mexico refused to pay for the wall, Trump had his quip ready: "The wall just got higher." How much, he didn't say. So let's just add One Trump.
A few days later in February
He liked this line! It was a winner. So at a rally a few days later, he said that the wall "just got 10 feet higher," again thanks to the Mexicans' intransigence.
He was referring to the conversation with Hall, but this time Trump had a hard number. So we can now put the Trump Wall at 45 feet.
When Wolf Blitzer asked Trump about Mexico paying for the wall during Thursday night's debate, Trump added another 10 feet, just like that.
About 20 seconds later on Thursday
Later in the debate, he referred to the height again. "We can do it for $10 billion to $12 billion, and it's a real wall," he said. "This is a wall that's a heck of a lot higher than the ceiling you're looking at. This is a wall that's going to work."
"Heck of a lot" is a subjective term, but we did our best to figure out how high we're talking.
The debate was held in the Moores Opera Center on the campus of the University of Houston. We called there to find out how high the ceiling was over the audience in the facility and were told that it was 45 feet high.
A 10-foot increase, then, is indeed a "heck of a lot" higher.
So there you go. As of this moment, until Trump randomly tacks on a few feet for whatever reason, the height of the Trump Wall is 55 feet. Please plan accordingly.
During Chris Christie's endorsement of his campaign (!), Trump added another ten feet.