The many challenges facing Trump's wall

President Donald Trump is following through with one of the first pledges he made a year and a half ago when he announced his long-shot bid for the White House -- directing federal resources toward building a wall along the southern border.
But the reality of building the wall could be more difficult than the rallying cries would suggest. The length of the wall, when construction will begin, how much it will cost and who will pay for it remain fundamental questions.
There is also ongoing debate about the feasibility of the structure and the need for it in the first place.
Trump's push for a wall dates back to the day in June 2015 when he announced his campaign and promised to "build a great, great wall on our southern border" and said Mexico would pay.
"Mark my words," he said for added effect.
His effort to turn those words into reality is expected to be formally announced Wednesday and is among several immigration-related actions anticipated in a multi-day rollout from the new administration.
Since he first made the pledge, walling off our neighbors to the south became an oft-repeated promise and rallying cry, both for the candidate and his supporters. Chants of "build that wall" thundered through arenas and convention halls. In at least one instance, Trump himself led the cheer. Building "an impenetrable physical wall on the southern border, on day one" is listed as item No. 1 on his "10 Point Plan to Put America First."

Reality of building the wall
At the first press briefing of the new administration Monday, one of the first questions to White House Press Secretary Sean Spicer was about the wall. Spicer said the administration was working with agency heads and Congress to move forward on the project. He offered no further details.
Donald Trump's immigration policy: Then and now
Not everyone is as enthusiastic as the President about building a wall, including the man whose job it was to secure the U.S. border for the past three years.
"I don't see any efficacy in building a wall across the border," said Gil Kerlikowske, who until last week served as Commissioner of Customs and Border Protection under former President Barack Obama.
"The border and migration issues are just unbelievably complex," Kerlikowske said in an interview with CNN. "And a simple answer to a complex problem is most assuredly the wrong answer."
Trump has yet to appoint Kerlikowske's replacement.