The other side of the coin is that these undocumented immigrants allow many citizens to enjoy a more functioning infrastructure, since so many of these immigrants work in the food industry and retail food stores, or other functions that are not high paid, and labor intensive. They work, and work, and work.
If all these immigrants left the U.S. tomorrow, and the cost to state and local governments suddenly disappeared, I am not naive enough to think any government would lower its taxes, or give a rebate to its citizens.
The reason that unlimited immigration ended in 1924, I thought, was a pro-nativist attitude that was gaining popularity. The U.S. has so much empty space, especially compared to Europe, I just think it's foolish to not fill the country up with people. But then again, not everyone likes a little competition in the marketplace or the educational system. Oops, I don't want to make this post like the Kings New Suit of Clothes.