for one thing, the US has a high profile global presence. when the US government or economy does something, people all over the world tend to hear about it and often react. sometimes it effects them in powerful ways (e.g. war, trade, Beyonce).
for another, the US seems to have evolved both the strongest individual free speech protections and some of the freest immigration policies and practices.
because of its global familiarity, in the last 30 or 40 years, many people from around the world have come to the US and felt comfortable exercising that freedom. maybe people think "if the US feels free to reach out and impact my part of the world, then i'm free to go to the US and impact it."
i don't know if there are other countries in a situation like that. maybe the UK? maybe China and India, if you consider the poor rural workers who've migrated into the big cities?
for another, the US seems to have evolved both the strongest individual free speech protections and some of the freest immigration policies and practices.
because of its global familiarity, in the last 30 or 40 years, many people from around the world have come to the US and felt comfortable exercising that freedom. maybe people think "if the US feels free to reach out and impact my part of the world, then i'm free to go to the US and impact it."
i don't know if there are other countries in a situation like that. maybe the UK? maybe China and India, if you consider the poor rural workers who've migrated into the big cities?