That means that about 7.2 miles of the border belong to ports of entry, which leaves 1,366.8 miles.
The result? We need about 4.6 million steel slats to cover that ground. At a height of 28.4 feet and a presumed thickness of one inch, each slat requires a bit less than 2 cubic feet of steel. For all of the slats, we’d need about 9 million cubic feet of steel.
As CNBC notes, that steel is a lot pricier than it was a year ago, thanks to the tariffs Trump imposed on foreign steel. At the beginning of 2018, this barrier would have cost 25 percent less.
Update: A civil engineer wrote in to note that, at current prices of $160 per cubic foot, the steel alone would cost about $1.5 billion – excluding steel that would need to be used to extend the slats into the ground. She also noted that a 1-inch-thick wall wouldn’t be terribly sturdy [www.washingtonpost.com/politics/…](https://www.washingtonpost.com/politics/2018/12/23/based-trumps-detailed-diagram-his-slat-wall-we-did-some-advanced-mathematics/?utm_term=.db6bf37e2657.)