The process for a foreign citizen to legally acquire a green card and eventually become a legal naturalized citizen of the U.S. is difficult, time consuming, and expensive. Many critics of the system maintain that if the process was simpler there would be far fewer foreign citizens entering and remaining in the U.S. illegally.

When a foreign citizen visits the U.S. as a tourist, a medical patient, a student, or for business purposes, they generally need to present only a valid national passport, a photo ID card or birth certificate, and sometimes an entry visa. A visa is simply an endorsement on a document that shows authenticity and conveys permission to travel to and to enter a foreign country. This type of visa is also known as a nonimmigrant visa. Fees for a passport, a nonimmigrant visa, and a border crossing card total about $300.

However, when a foreign citizen wishes to reside and work in the U.S., they need to present an immigrant visa, also known as a green card. The green card was originally called the Alien Registration Receipt Card, but it has recently been renamed the Permanent Resident Card. Originally the card was green in color but now the card is white with some green printing on the back. It is still known generally as the green card. Recipients of the green card must carry it with them at all times. The green card is valid for a period of 10 years.

The green card is issued to a foreign citizen as a response to a petition by an employer or a relative who is a U.S. citizen. The petition by the employer or relative allows the foreign citizen to enter the U.S. for the purposes of being employed and residing permanently in the country.

The process for acquiring the green card generally follows three steps. The U.S. Citizenship and Immigration Service (USCIS) issues the green card. This service used to be known as the INS or Immigration and Naturalization Service. USCIS is often referred to as simply the Immigration Service and is now part of the Department of Homeland Security. The first step is for the USCIS to review all of the paperwork and approve the petition from the qualifying relative or employer. The second step is to send the approved paperwork to the National Visa Center (NVC) where the petition waits for a visa number to become available. Only a limited number of visa numbers are available each year. Once a visa number becomes available, then the third step is for the petition to be forwarded to the appropriate U.S. embassy or consulate in the foreign citizen