The vast majority of illegal immigrants in the United States come in legally, at first, through air and sea ports.
This is incorrect. 40% of illegal immigration is from visa overstays, which is not the vast majority. References:
http://www.wsj.com/articles/SB10001424127887323916304578404960101110032http://www.npr.org/templates/story/story.php?storyId=5485917Building a 40 billion dollar 30 ft wall all along the U.S.- Mexico border (the projection for building and maintenance keeps getting adjusted) can be breached by a 35 ft ladder and a rope (or a tunnel).
Of course a wall isn't going to stop 100% of people, but it might be 95% effective, and 0.05 * N is much, much smaller than 1.0 * N. Try applying such logic to anything else in the universe. Window screens don't keep out 100% of insects. Sunscreen doesn't block out 100% of UV. Medicine doesn't have a 100% cure rate. That doesn't make mean they aren't highly useful to employ.
Walls and fences are quite effective in greatly reducing encroachment, which is why they have been used from antiquity through today, where they continue to be widely used around military bases, airports, schools, high-end homes, the Vatican, Israel, secure storage locations, power plants, electrical substations, water-treatment plants, construction areas, pools, parking areas, ports, and so on.
Here is an example (which some people keep ignoring) *directly* relevant to the discussion.
Hungary built this along its border (it took less than a month to do it):
And this was the result, 4000-8000 illegal immigrants per day before vs. (on this scale) zero after:
Is that fence useless? No. Are 6000 people per day going over it with a ladder or rope or under it with a tunnel? No. Do you think that, even if some tunnels were dug, still 6000 people per day would go through them, or would it put a significant crimp in the flow?
So, let's talk about the costs. $40B. Let's look at that from two perspectives.
First is that our government spends $3.5 trillion per year. If the project took 4 years (likely hugely optimistic), that would be $10B per year, or 0.29% of the government's yearly spending. If you are a Keynsian (are you?), you wouldn't care about that anyway, since the larger the money spent, the better anyway. (It is interesting that many of the factions against a border fence are Keynsians yet use the cost as an argument against a fence -- I'm shocked at the hypocrisy.)
Second, there is the cost of illegal immigration. All references for these numbers are given below. It costs $10,000 to deport a person. Illegal immigrants cost the US $113B/year as of 2011. As of 2011-2013 or so, there were an estimated 20M illegal immigrants in the US. As of 2000-2005, there are 850,000 new illegal immigrants per year coming in.
So, the cost of a fence is about 1/3 of the cost for one year of illegal immigrants in the US.
Also, assuming an illegal immigrant spends 5 years here before getting deported (my guess is that the average stay is more like a lifetime, not 5 years, but I'll be conservative here in a direction that disfavors my argument), the cost per new illegal immigrant is the cost of his stay plus the cost of eventual deportation = 5 * $113B/20M + $10k = $38k. Assuming a wall reduces illegal border crossers by 50% (an unrealistically low estimate, I think, based on Hungary), and assuming our current border crossers are 60% of only 850,000/yr (data as of 2011 -- I'm not assuming any increase since then), a wall would reduce crossers by 255,000 people/yr. Under those conditions, the wall is paid off in 4 years, and after that is generating $10B per year in cash flow.
So, there you have it. An argument based not on purposefully misleading leftist -- or rightist -- propaganda but on published numbers and using straightforward math.
You should now be convinced.
References:
http://www.csmonitor.com/2006/0516/p01s02-ussc.htmlhttp://dailysignal.com/2015/12/27/you-only-think-you-know-how-many-illegal-immigrants-live-in-the-us/http://www.migrationpolicy.org/article/frequently-requested-statistics-immigrants-and-immigration-united-states/#Unauthorized%20Immigrationhttp://www.fairus.org/docs/poverty_rev.pdfhttps://www.americanprogress.org/issues/immigration/news/2015/08/18/119474/what-would-it-cost-to-deport-11-3-million-unauthorized-immigrants/