This is an oversimplification of a very complex issue, but…
NAFTA, basically. The North American Free Trade Agreement made imported goods in Mexico cheaper than goods produced in that country. People stopped buying locally. It also became really easy for foreign companies to come into Mexico, set up shop, hire cheap Mexican labor and export the goods. So investment in the country basically went all to hell, and as a result the agricultural sector collapsed. It became very difficult to make a living in Mexico (I mean, even harder than it already was) and thus immigration to the U.S. exploded.
I saw a little of this impact firsthand when I volunteered in Mexico many moons ago. The farming community where I was staying had been reduced to about 1/10th its original size. 90% of inhabitants had gone either to the city (Mexico City) or up north (to the U.S.) in an effort to make a living. I remember talking to a young girl about her life plans, she couldn’t have been more than 12 or 13, and her plan was to hire a coyote to take her to Canada.
A lot of people saw it coming and were opposed to NAFTA for that reason. But NAFTA had immediate economic benefits for the U.S. which made it really popular politically.
That’s one part of it. Additionally, many U.S. businesses actively seek illegal immigrants to hire because they don’t have to pay them as much (or at all, as the case often is) and they don’t have to deal with those pesky workplace safety regulations. The bottom line is, illegal immigration is good for business in the U.S., and as long as that continues to be the case, nobody is going to do a damned thing about it.
Interestingly, Obama has been pretty tough on immigration. He’s arguably deported more people than any other president we’ve had, though he’s lied a lot about that and said a lot of things that would make you think otherwise.
This perspective brought to you by a woman who was once heavily involved in social justice for Latino immigrants. I had some colleagues who are DREAMers, bright young college kids who were brought into the U.S. when they were very young and are fighting to stay in the only place they know as home. They are very active in advocacy and legislative policy and more than once they’ve allowed themselves to get arrested so they could draw attention to the conditions of deportation facilities.
As for ‘‘open borders,’’ the general rule of thumb is that the more immigrants a country has coming in, the more tough they are on immigration. There are some countries who used to have quite lax immigration laws who have received a tremendous amount of social pressure as immigration to that country ramps up and the immigrants become more visible. I think this is because people are inherently xenophobic and feel threatened by cultures that are not their own.