Having just won their freedom from England, the United States started setting up rules and laws to govern their new country. They soon realized they needed rules to deal with immigration and citizenship. This resulted in the Naturalization Act of 1790. This act said that an immigrant had to live in the United States for a minimum of two years. Then the immigrant had to make an oath to the new government and renounce monarchies. During this time Congress limited the people that could do this to white, land-owning males.
This law did not last long. In 1795, Congress passed another act extending the time to a five-year residency. Several more rules passed throughout the years. Eventually, we arrived to today where anyone could obtain residency in the United States after following certain steps.