I think for the most part; illegal immigrants have worked very well for the US, it provides cheap workers without any sort of burden on the tax payer (in theory). However i think that might be changing and now they are seen as a tax burden (car accidents, medical expenses, no tax income ect), in other words people who are not paying tax are needing services.

It's hard to change as 1/2 of cali is latino and the other southern states pretty much rely of them to hold the low pay jobs. i think a more open and transparent visa program might help, you don't want to force people to assimilate, you want them to become paying and well defined parts of the tax system.