Here's a great story from NY Daily News about the US Olympic Team and how immigrants made up a huge part of it. From the article:
Winning Olympic medals is nice for patriotic spirit and national prestige, but there’s a bigger point here that goes beyond the world of sports. It's easy to count medals and see how much immigrants have added to American athletics. The contributions in science, business, art, music and cuisine can be harder to quantify, but they are there, too. Close the immigration door tighter, as restrictionists recommend, and we’d have fewer Olympic medals, but also fewer scientific discoveries, fewer successful high-tech startups and fewer worldwide hit songs. Open it wider, and we’ll have more.