1.) More enforcement on the US side - The Obama Administration's Secure Communities program and its record number of deportations, states like Alabama and Arizona passing "get tough" laws, and double the number of border patrol agents.
2.) The downturn in the US economy - Construction and manufacturing jobs are simply not available any longer.
3.) The improving Mexican economy - Most Mexicans would rather stay home, and with higher wages, better access to education and more jobs, many are finding that a more viable option.
4.) Crime in Mexico - Immigrants coming from beyond Mexico's southern border have been driven away by Mexico's high crime rate and the drug war that America pushes on the Mexican government. This has led to high rates of murder, kidnapping, drug and human smuggling crimes.
So essentially, many Americans have gotten exactly what they've been asking for - far fewer Latino immigrants in America. (It makes me wonder why they're still complaining!?) But let's examine why each of these items could be bad for Americans.
1.) More enforcement on the US side - Secure communities and Obama's deportations are costing this country literally billions and billions of dollars at a time when our government is already bankrupt. The vast majority of those being deported are simply here to work and make a better life for their families, so the fact that our government is wasting money on sending them back to their home countries is foolish at best and evil at worst. Yes, we should jail or deport criminals who violate the rights of others, but deporting a productive mother of three children for a minor traffic violation is simply ridiculous.
2.) The downturn in the US economy - This obviously isn't good for anyone. With unemployment rates in some US states at just under 10%, America is definitely in need of more companies such as Google, Dupont, Intel, Carnival Cruise Lines and others, all of which were founded by immigrants. In addition, struggling US companies could really use an inexpensive labor pool to help them stay in business. And finally, US farmers need people willing to do the back-breaking work of harvesting and planting crops. Inexpensive products and services, lower food costs and jobs creation is definitely something that would be a benefit to all Americans and the people who migrate here.
3.) The improving Mexican economy - While the improving Mexican economy is good news for the entire global economy, the lack of immigrants from Mexico means that the affordable labor pool in America may be drying up. That will lead to higher prices on the goods and services Americans have become spoiled to. Of course, we wouldn't have to rely on affordable immigrant labor if our own government would butt out of the economy. Minimum wage and other labor laws need to be repealed and businesses need to be free to manage their companies as they see fit. This would lead to more American jobs, albeit with lower wages, but our cost of living would also decrease so we could live on the lower wages. That being said, the government shows no signs of letting the free markets reign, so cutting off our cheap labor supply only signals more troubled economic times ahead for Americans.
4.) Crime in Mexico - Crime in Mexico is obviously bad for America, particularly land owners along the US' southern border. It is not right for the property rights of Americans living along the border to be violated on a daily basis by human and drug smugglers; however, we need to put the blame for this problem where it rightfully lies, on the US Government. The government has created black markets in both human and drug smuggling, which accounts for the vast majority of crime along our southern border. Like Prohibition in the 20s and early 30s, when the government tries to legislate morality, all they successfully do is raise the crime rate and create criminals where there would otherwise be none. The government's only proper function is the protection of individual rights and it should protect the rights of US citizens along the border by passing meaningful immigration reform and repealing drug laws.
The bottom line here, once again, is that America is hurting due to a lack of capitalism. Capitalism, as Ayn Rand states, "is a social system based on the recognition of individual rights, including property rights, in which all property is privately owned." If men are left free to trade with each other voluntarily, as they see fit and act in accordance with their own best interests, you will see prosperity unlike any country, including America, has ever seen. Once again, I strongly encourage everyone to read Capitalism the Unknown Ideal and educate yourself on the true meaning of real capitalism, not the mixed-economy, mixed-socialist mess our country now suffers from.