How did immigrants assimilate?

Mostly, because they are proud of being Mexican and they have a long history backing their beliefs; also, the language barrier (most of them speak Spanish), religion (Roman Catholicism) and culture...

An imicrant would lean the history, customs and language of his or her adopted land.

Nativists are people whom do not like and usually discriminate against immigrants. Therefore, they feel as if immigrants will not be able to truely assimilate into the new culture that they have...

Very much so. It would benefit them if they did. Many were fleeing from unfriendly regimes.

Yes. A hyphenated-American is a non-American. If their former culture is so important, they should return there and leave America to those who choose to join and become an asset instead of a dividing...