A big part of the problem with illegal immigration in America is that while immigration policy and enforcement is purely a jealously guarded function of the federal government, the costs associated with illegal immigration are paid overwhelmingly by state and local governments. I think we could make a lot of headway with illegal immigration if we required the federal government to reimburse state and local governments for all costs associated with dealing with illegal aliens.
At present the federal government requires that states provide the same level of services to illegal aliens that they give to citizens. They must provide medical care, education, social services and criminal justice. This arrangement provides no incentive for federal politicians to try to reduce the burden on localities caused by illegal immigration. They can strike a moral pose about the sanctity of immigration to America while letting the politicians lower down on the food chain deal with the negative consequences.
Letting the states bill the feds for the costs associated with illegals would hit the politicians in the wallet. If they had to choose between paying for their pet projects and paying for illegal immigration, they might view the problem with the same urgency as do those who pay for it now. Politicians who represent areas without substantial illegal immigration might suddenly discover that the entire country might have a problem.
There is little argument that low-skilled illegal immigrants are at first net consumers of tax dollars. Only over the course of decades, as they follow the American dream up through the tax brackets, do they become net producers of tax revenues. Areas that must absorb large numbers of new illegals must often raise taxes or cut services to everyone to compensate.
It is profoundly unfair that a minority of localities must pay for failed federal policy. Immigration is a federal issue. The feds should pay for it.