Immigration of people from other countries is one of the most debated issues in the U.S. with spirits being still high amid the immigration reform bill that was introduced in the Senate in April by the so called "Gang of Eight", a group of eight senators who negotiated and wrote the bill. And while it's still not clear what will happen with the bill at the House of Representatives, the problem of immigration is still a serious one with many arguments both in favor and against the facilitation of immigrants to work and live on the territory of the United States.
Immigrants in the United States came from almost every country in the world, since the idea to pursue the "American Dream" is infilitered in the life of every human that lives outside the U.S. since childhood through movies, music, magazines, videogames, etc. However, the main flow of immigrants come in the U.S. from its southern neighbor, Mexico, followed by China and India. You should go to the website of Insider Monkey to know more facts about immigrants.