Admission into the United States
Everyone arriving at a port-of-entry (airport, land, or sea) to the U.S. is inspected by U.S. Customs and Border Protection (CBP) officers. CBP officer will conduct the immigration, customs and agriculture components of the inspections process. If a traveler has health concerns, he/she will be referred to a Public Health Officer for a separate screening.

Before landing in the U.S. at a port-of-entry (the international airport where you land), one 6059B - customs form will be given to each family. Prior to May 2013, all nonimmigrants to the U.S. needed an additional form,  Form I-94 (Arrival-Departure Record) or Form I-94W (Nonimmigrant Visa Waiver Arrival/Departure Form). Paper I-94 and I-94W forms are no longer distributed as of May 2013. Flight attendants will distribute this form prior to landing in the U.S. If you need any help filling out the forms, ask the flight attendant for help.

Fill out these forms using only capital letters. Wherever they mention TYPE or PRINT, it means you should not write in cursive letters but with normal letters. If you took several flights to the U.S. and had to transit through one or more countries to reach the U.S., you should mention the flight number of the last flight that brings to you the U.S. and the last city/country you boarded from.

Keep your watch in sync with current time zone as you get out of the plane. Take all of your belongings, including hand-baggage, and start walking towards the immigration check.

Upon arrival, follow the signs for immigration. The airline personnel will guide you to the inspection area. There may be separate lines for U.S. or Canadian citizens (Orange color), people from Visa Waiver Countries and Lawful Permanent Residents (yellow color), people with no checked luggage (green color) and all others such as regular visitors and temporary workers. At many airports, there are automated passport control where you don't have to see the officer but go through the steps at the automated kiosk.

Depending on your legal status with respect to the U.S., you may need to present different documents.
Admission Documents

Keep the  completed form in the passport. In addition, make sure all other applicable papers are ready just in case. Everyone in the family can walk together to the immigration counter.

If you are a U.S. citizen, the officer will ask for your passport, verify your citizenship, and then welcome you back to the United States.

Effective May 2013, a stamp in the passport shows the date you arrived in the U.S. and the "admitted until" date, or the date when your authorized period of stay expires. (Earlier to May 2013, the stamp was put in I-94/I-94W/I-95 form instead.)

During the inspection, a CBP officer (immigration officer at the port-of-entry) may ask you several questions about the purpose of your trip, how long you will be in the U.S., where you will stay, and your residence abroad. Talk absolutely to the point. Do not try to lie. Make sure that whatever you say is written on the paper. Keep you answers simple and to the point, such as "6 months" or "visiting my son and seeing tourist places."

After successfully completing your processing, a CBP officer will stamp your passport and the customs declaration form. He/she will stamp your passport, signifying that you are permitted for an appropriate duration, e.g., six-months stay (for visitor visa holders) or for 3 years (H1B/H4 visa holders). The passport stamp indicates a date, which is the latest date you are allowed to be in the U.S. Prolonged stay after that date is illegal. Do not lose it.

All non-U.S. citizens will be fingerprinted and photographed under a program called US-VISIT.

Prior to departing the area, review the class of admission (such as B-2 for visitors, H-1 for temporary workers, F-1 for students, etc.) and period of admission recorded on the admission stamp. If there are any mistakes, it is best to have them corrected right away. The information written by the officer in the passport stamp at the port of entry is the basis for all further immigration-related activity in which you may engage while in the U.S. Benefit agencies, namely the Social Security Administration, make decisions based on the handwritten endorsement recorded on the passport stamp and previously on Form I-94.

File Form I-102 for correcting errors later. Even though paper I-94 form has been eliminated, you may still need it for various immigration related purposess. You can print it online at CBP website.

If you would like to extend your stay beyond the date in the passport stamp (previously in I-94 form), you will need to file Form I-539 . You may need to file additional paperwork depending on the type of nonimmigrant visa you are extending.
Visitors Visa Extension

Many people who come to the United States on nonimmigrant visa are confused regarding the duration for which they can legally stay in the United States. The visa stamp is used just to enter the United States. You can enter United States at any period during the validity of the visa. (Whether you are permitted to enter once or multiple times is dependent on whether your visa is single entry or is multiple entry.) At the port-of-entry, the immigration officer determines the duration for which you can stay in the United States. That is the legal period for which you can stay. For example, if you are traveling on a visitor visa and your visa is expiring next month, if the immigration officer grants you six months' stay, you can legally stay for six months.

More details on visa stamp vs. authorized duration.

Once you are in the United States, you are free to travel wherever you like without needing to follow any preset itinerary or check in with any government officials.

Form I-94 and I-94W
Update: Paper I-94 and I-94W forms have been eliminated since May 2013. If you need it for any purpose, you can print it from CBP website.

Entering by Land
The general entry process at a land border port-of-entry is similar to that described above. A CBP officer will conduct the primary inspection in the vehicle lane. If required, the CBP officer may send you to a secondary inspection area for further review or issuance of needed papers. Once the officer determines that you should be allowed into the United States, you will either be sent for further customs inspection or immediately allowed to proceed on your trip.

Alien truck drivers may qualify for admission as B-1 (business) visitors to pick up or deliver cargo traveling in the stream of international commerce.

Entering by Sea
The general entry process at a sea port-of-entry is similar to those described above, if inspection facilities are available. Otherwise, passengers will be instructed as to where they should report for inspection on board the vessel.

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