The United States is a nation built by immigrants and their descendants. In the late 1800s, many immigrants from different part of the world left their home countries and came to the US for better economics opportunities. Back in their home countries, they were facing famine, agricultural failure or instability . Today, there are various types of ethnicity from different countries living in the US, and still a lot of people from different parts of the world looking to work in the US.
There are many types of immigrants coming to the US every year, such as family immigrants, Middle-Easterners worked for the US military and skilled employment immigrants. Foreign family members coming to reunion with their American family members is the biggest source of immigrants. They made up 86% of the total immigrants in 2016. Meanwhile the employment-based immigrants are only made up of 4% of the total immigrants. These percentages may change after Trump is elected as he might alter the current immigration policies.
For foreign workers and students studying aboard who are looking to work in the US, they are required to have the H1B visa. It is very common to see in job boards about whether companies are sponsoring the H1B visa for their employees or not. This visa last for six years. After six years, the H1B visa carrier will need to be renew their visa if they wish to continue working at the US.
Many of the H1B visa carriers are skilled labors and they are working in large firms at Wall Street or Silicon Valley. Most of them have professional titles like engineers, analysts, scientists, accountants, consultants, or developers. They are also working for different industries.