Your ignorance is the evidence. A valid social security number is required for filing taxes and receiving a tax refund. Instead, undocumented people pay taxes and pay for services Americans all use like Medicare and Social Security. Plus, they do jobs lazy Americans scoff at. Without undocumented immigrants, a steak at the supermarket would cost $200 and lettuce would be $20 per head. So take your thinly-veiled, provincial xenophobia, and shove it up your ignorant behind where it belongs.