At first we should occupy ourselves with countries which are can be respected to be traditional immigrantion - countries, for example the USA.
At the end of the 19th century the German Reich founded colonies, because among other things the Reich didn´t wanted that too much Germans emigrating to America, which would be lost to the German nationality. In fact the relative majority of the US - Americans has got German ancestors.
Emigration respectively immigration causes inevitably - at the latest during the third generation - the loss of the old ethinc and cultural indentity of the immigrants. The rising up of parallel societies is being unwelcome at the side of the immigrantion - countries.
But we cannot speak about a real integration in the case of the USA. The question to integrate immigrants wasn´t asked, because an absolute new society and state should be set up, so that a multicultural society could rising up. Surely this plan couldn´t be realized in a short time, the aparthid was just abolished during the 1960ths.
Nevertheless each group of immigrants had got the chance to insert their cultural goods. Although of the majority of Americans of German descent the German language couldn´t make its way to become the official language, but a certain influence of German to the American - English language can´t be ignored.
A lot of German immigrants got conscientious doubts, because the German Reich and the USA made two fierce wars against each other during the 20ths century. The now homeland demanded solidarity, even at the price to shoot dead former fellow - countrymen.
But this conficts could be overcome during the time. The USA - in former times as racist as Nazi - Germany - have delevolped themselves succesfully. So we can be hopeful for the future, but a lot of things are still remaining to be done.
But problematically is the still till today mostly very reactionary population of the USA:
* the population of the USA is more religious than the population of any other industrial country. Religious funamentalism of each kind is playing a decisive role. Atheists and homsexual persons are being persecuted but at least discriminated in some regions of the USA, for example in the so called biblebelt. A lot of people would prefer a theocratical system, comparatively to Israel.
* the birth rate of the USA with about two kids per woman is being clearly higher about 0,5 kids than in Canada and in Europe.
* a certain arrogance of the US - Americans respecting their thinking to be the only right way the rest of mankind has to accomodate itself.
* the acceptance of nuclear - weapons and archaic thinking, like the support of the capital punishment, are very popular.