Is there a Central South American country that is not a mess or worse? Maybe Chile? The US is closer and easier to get to. Keep in mind, too, that California, Arizona, New Mexico, and Texas have had Spaish-speaking people since those states were Spanish colonies. "Immigrants attract immigrants" is true - consider how many cities had Jewish, Italian, Polish, German*, etc. enclaves - but is an over-simplification.
* The town near which I grew up reached 10K population somewhere around 1951 or 1952. The Lutheran church in that town did not move from services being in German to services being in English until some time in the late 1930s. The town had quite a few families who were Volga Germans, German-speaking people who had left the Ukraine in the early 1900s, anticipating what Russia would become.