America a nation of immigrants?

Numbers are incredible United of America is the first of land immigration in the world. 12% of the population was born in foreign country.
This number are consequence of the history of immigration to the USA.

Indeed since 1607 America was considered as the promissed land. As a result there were many immigration waves ; to begin in 1607 the first colony was establised in Virginia by a group of bristish merchants with black slaves. But it was in 1620 the Puritans ,who fled England for religous reasons because of persecution, wanted to build a new country, they later became known as the Pilgrims Fathers .
Then from 1800 to 1880 the were others immigration waves ,because of potato famine in Ireland and Napoleonic and revolutionary wars some Europeans decided to come in America for poverty, famine persecution and wars, they mixed with the existing population to make the WASP (White Anglo-Saxon Protestant) stock. Finally from 1880 to 1924 new immigrants came from Southern Europe ( Italy, Sicily, Greece, the Balkans),Central ans Eastern Europe (Russia, Hungary, Poland, Rumania) and the Far East (China, Japan, Korea), the Asian population represed the cheap labour force but all the same the WASP population feld threatened by their numbers and different lifestyles. That's why in 1929 Quota Laws were established to protect their culture and their language.
Now the greater part of new immigrants come to Mexico,they dare cross a barded wire and a desert to come in USA. They also try to escape the poverty in their land.

Often we wonder why immigrants come to USA. They want to start a new life far poverty, persecution and wars. They are scared by the racism persecution in USA.
On the whole USA, who is still the promissed land for many people, has appeal radical precaution as the barded wire between the american and mexican border. Is this necessary? Can it stop immagration?The one who was considered for a long time as an