Thundarr,
First we should differentiate between legal and illegal immigration. The way to control illegal immigration is to control the demand side of the issue. It (the demand side) rests with the corporations and businesses that hire these people, pay them cash, way below living wage, avoid paying taxes, and exploit them 16-18 hours days. When President cracks on his corporate friends, including the nominee for Labor Secretary, then we will solve the problem. The wall is not going to solve it, because it is not possible to build it, owing to terrain. And now the Republicans are telling Trump that it will cost 2 times more to build it. Mexico already shown their middle finger to Trump's suggestion that they pay for it. Now Trump says that he is going to impose 20% import tax for goods from Mexico, in order to pay for the wall. Guess what, that 20% surcharge is going to be absorbed by the American consumers. This is what happens when you make policy based on ideology, instead of pragmatism.
We need legal immigration in order to maintain our competitiveness, especially in high tech, innovation, and cutting edge research and development sectors. When the chief strategist of our President says that Asian CEO's of Silicon Valley make him uncomfortable, when he starts re-designing visa policies to keep these "uncomfortable" people at bay he inadvertently poses risks to our competitiveness. After these announcements, countries with rather restrictive immigration laws (like France, Germany, Belgium) said they going to lure American researchers. Now you tell me that this is a prudent political move. What danger do intelligent, talented people of any origin pose to the US? they enrich us, contribute to the development of our country, etc.