Why has immigration become more of a problem in the last few decades?
I would argue that some of it, at least, has to do with increased wealth among those who would emigrate. It is not easy to drop the few possessions and relationships you have to embark on a journey to an unknown land far away in hopes of a better life. The least mobile are always the most poor. We see this to be the case at all levels. Within our cities, the middle class are infinitely better placed for upward mobility than anyone on welfare. In accord with my thesis, they are also more likely to take a new job in another locale. Often new employers help to pay for such a move. A potential employee has to promise a marginal productivity equivalent to the combined compensation of wages and moving costs. The more productive the individual the more sought after they become in the jobs market, and the more likely they will move.
Mexican immigrants promise a high level of marginal productivity to those that employ them, especially since they do not enjoy the protections of citizen enfranchisement.
Which leads me to another tangent. I’ve often noted that open immigration is a preferred policy, but that it would require an end to welfare. The same is true about other state protections. Citizens enjoy unemployment insurance. This, too ought to be done away with. OSHA protections must be eliminated. Social Security is a hindrance.
Free labor is what is really is being debated. Unfortunately for many citizen-workers, they will be more defensive of their privileges, their inherited “Labor-friendly” laws because they intuitively see the world as a zero-sum game. This is the case for most non-economists. If the creation of wealth could be demonstrated, if we could show that each new immigrant adds more productive wealth to the economy than they could ever possibly consume, if we could convince people that it is in their own best interests to take ownership and responsibility for their own labor, life, and livelihood, if we could do these things, and finally, miraculously, change the mentalities of so many who prefer security to liberty, then we might be able to get the laws which are best for us. This is unlikely.