The immigration laws in the United States have experienced uneven progress. During colonial times independent colonies created their immigration laws.The first attempt to naturalize foreigners was through the Naturalization Act of 1790. However many years later the Chinese Exclusion Act was passed to stop the immigration of Chinese people. The Immigration Act of 1924 put a quota on how many immigrants are permitted, based on nationality. The Immigration and Nationality Act of 1952 led to the creation of the Immigration and Naturalization Service.

The five major departments of the federal government involved in the immigration process are the Department of Homeland Security, the Department of Justice, the Department of State, the Department of Labor, and the Department of Health and Human Services. Of the five, the Department of Homeland Security, which replaced the Immigration and Naturalization Service, enforces immigration laws and bestows benefits on aliens. It is subdivided into three distinct departments: US Citizenship and Immigration Services, Immigration and Customs Enforcement, and Customs and Border Protection.

Every year, the Federal government conducts a Diversity Visa Lottery. The lottery grants citizens of other countries legal entry into the United States. However only countries “with low rates of immigration to the United States” are allowed to apply.

Presently there are two different types of US visas: one for people seeking to live in the US; termed Immigrant Visas, and the other for people coming for limited durations, termed Non-Immigrant Visas. The former visa has “per country-caps”, and the latter does not. Most non-immigrant visas are for work purposes, and usually require an offer of employment from a US business. Other categories include student, family and tourist visas.

The United States allows more than 1 million aliens to become Legal Permanent Residents every year, which is more than any other country in the world.

Immigration law became a serious political issue in the USA, particularly after 9/11.