[familyop]

The following should clear the political ties up enough, although hundreds of other bits of evidence are out there.

From the Libertarian Party site:

The benefits of open immigration
BY MICHAEL TANNER

Excerpt:
"Confirmation can be seen in a study by economists Richard Vedder and Lowell Galloway of Ohio University and Stephen Moore of the Cato Institute. They found that states with the highest rates of immigration during the 1980s also had the highest rates of economic growth and lowest rates of unemployment...As Edward Crane, President of the Cato Institute, has put it: "Suppose we increased the level of immigration..."

[KarlInOhio]

"Confirmation can be seen in a study by economists Richard Vedder and Lowell Galloway of Ohio University and Stephen Moore of the Cato Institute. They found that states with the highest rates of immigration during the 1980s also had the highest rates of economic growth and lowest rates of unemployment...As Edward Crane, President of the Cato Institute, has put it: "Suppose we increased the level of immigration..."

That cart is doing a great job of pulling the horse. It is more likely that immigrants (both legal and illegal) moved to those states that were growing quickly and had upward pressure on wages because of low unemployment. Immigration didn't cause the growth - the growth caused the immigrants to move there.