https://www.washingtonpost.com/worl...28c0aa-cec7-11e6-b8a2-8c2a61b0436f_story.html
https://www.washingtonpost.com/worl...14789c-ab59-11e6-8f19-21a1c65d2043_story.html
15% increase in illegal border crossings in 2016 with the majority coming from Honduras, El Salvador, Guatemala etc. Most of it is that once they crossed, before Trump came into power, applying for asylum, they would be detained and held and then processed and let go with a promise to appear, which many don't do. It is not so much Mexicans anymore but other central and latin american groups fleeing violence and gangs and poverty etc. Now think about it, you have a 30 foot tall barrier where nothing is now, where are the people going to go so easily? Those articles show the difficulties faced by both US authorities and then migrants/refugees etc.
Your articles don't say that 90% of illegal/undocumented immigrants cross at unguarded parts of the border. Without at least 90% doing so, your figure is bullshit. Then there's the fact that a gigantically long wall is not going to be impervious. If people are sneaking across now, they will still do so even with a wall in the way.
Would a theoretical wall covering the entire length of the border make it harder for some people? Sure. Not anywhere close to stopping 90% of them, and you would still get people and smugglers circumventing it. This all still aside from the high likelihood that the wall will never be finished to begin with.
If undocumented immigrants are such a problem, the U.S. should focus on the reasons why people are migrating, and work on the source of it, not blow billions on something that does little to nothing, and will cost gigantic amounts to staff and maintain.
The way things are going, the U.S. is more likely to find its immigrant troubles reducing because it's become a shithole people just don't want to go to anymore, over some magical wall.