@livinglava,
The United States probably has the world's best by far record for the real cultural and economic assimilation of immigrants. The millions of Germans, Scotch Irish, Irish, Chinese Scandinavian, Czech, Polish, Jewish and Italian and their steady upwards trajectories in American life amply testify to this fact.
Just what was our "system" for doing this? In fact, other than economic freedom to pursue their ambitions unassisted, there was no "system" at all. Each in turn was initially a despised minority, known as "Kraut", "Mick" or "Paddy", " Chink", "dumb Swede", "Hunkie", "Kike, or "Dago" or " Wop". The trajectories they pursued initially included laborer, farmer, crime. professional sports and quickly moving up to skilled worker, entrepreneur, government employee and finally professional pursuits. The same path was subsequently followed by Latinos of many origins and many others. Each in turn won its own self-respect and the, usually grudgingly given, respect of whatever was the establishment of the time and place, and each made its own lasting contributions to our cosmopolitan culture. Slavery and Jim Crow stopped the clock on this process for African Americans for too long, but it is happening now. Jason Reilly's work "Please Stop Helping Us" comes quickly to mind here.
No European or Asian country has come close to us in this respect. Australia and Canada have come fairly close but mostly only in the last two generations.
I believe there is a fundamental lesson here. Freedom and economic competition are the real drivers for assimilation, and no government program has ever equaled this basic process in the results it achieves. Government efforts at "protection" and "levelling the playing field are quickly corrupted by people acting in their immediate self interest and the result is that the wrong people and behaviors get rewarded and amplified.