If you're coming to the United States as an immigrant or with a nonimmigrant visa (or from one of the countries that doesn’t require you to have a visa), the first person you meet on arrival—whether you come by air, land, or sea—will be an officer of Customs and Border Protection, or CBP.
The officer will inspect your passport and documents, looking for verification that you've been given permission to be in the U.S., as well as any information that might prohibit you from doing so. If entering on an immigrant visa, you will need to hand over the sealed, unopened envelope containing your visa documents.
Have all your paperwork ready. CBP officers are trained to be skeptical, and security is their first concern.
You might encounter delays as your name is checked against various computer databases. The officers are also on the lookout for people using a tourist or other nonimmigrant visa to gain entry to the United States for illegal purposes or a permanent stay.
Even if your visa and intentions are valid, if the CBP officer finds a problem or believes you're lying or are a security risk, you can be refused entry at the border, returned to your home country, and prohibited from returning for five years.
One way to ensure a smoother, shorter entry to the U.S. is to apply to a U.S. government Trusted Traveler program, available only to people from countries considered low-risk. Approval will mean that, instead of standing in the long passport-control and inspection lines, you will be able to enter using a kiosk (located at designated U.S. airports). The exception is if you are bringing in certain goods or large amounts of currency, in which case you must go through the main inspection line even if you've been approved as a trusted traveler.
Here are the most likely questions you'll have to answer. However, the officer is free to ask you just about any question. You'll increase your chances of being treated with respect by remaining polite and calm.
Why are you visiting the United States? Your answer must match your visa (or the legal requirements for admitting you without a visa). If, for example, you have a B-2 visitor visa but say that you're coming to find a job, you'll be put on the next flight or bus home. Or if you're entering with a marriage-based green card, you obviously don't want to say, "To start a revolution." Your answer must show that you don't plan to violate any U.S. laws.
Where will you be staying? Particularly if you're coming for a temporary stay, the officer wants to know that you have clear plans for what you will be doing in the United States. If you have no previously arranged places to stay, the officer might question whether you should be allowed in.
Who will you be visiting? Again, this is a question directed mostly at tourists. The officer is looking to see that you have clear—and legal—plans.
How long will you be staying? If you're coming in with an immigrant visa (have been approved for permanent residence), you won't likely be asked this. For short-term visitors, however, the officer wants to know that you don't plan to stay longer than you should. Even if your visa says "multiple entry" or "one year," you may not be allowed to remain for that length of time—the I-94 arrival/departure record that’s created for you (if you’re arriving by land, with some exceptions, such as Canadian tourists) will tell you the date by which you must leave. The I-94 is available only online, at https://i94.cbp.dhs.gov, if you arrive by air or sea. Others will receive a little white card stapled into their passport.
How much money are you bringing? This is a question for temporary visitors; the officer wants to know that you will be able to cover your expenses while in the United States.
Have you visited the United States before, and if so, did you remain longer than you were supposed to? If you have previously stayed in the United States for six months longer than you were allowed, you may not be eligible to come to the United States again without special permission called a waiver (unless you've waited outside the United States for at least three years). If your overstay lasted a full year, you might be punished by having to remain outside the U.S. for ten years before trying to return.
How often do you come to the United States? The officer is looking for people using a tourist visa (or the right to enter without a visa) as a way of living permanently in the United States. Those who do so will be accused of misusing the visa and be denied entry.
Foreign nationals attempting to come to the United States, either temporarily or permanently, have few rights during the application and screening process. You cannot have a lawyer represent you when you attempt to enter the U.S., nor are you allowed to call one if problems occur during your interrogation. Your bags can be searched without your permission, and CBP officials can ask you almost any question.
Also see Are U.S. Border Officials Allowed to Search a U.S. Citizen's Phone, Laptop, More?, the analysis for which also applies to U.S. permanent residents.
Only in rare cases, such as if you fear persecution in your home country and are seeking protection (asylum), and the CBP officer believes that your fear is credible (believable), will you be allowed to appear before an immigration judge to prove that you should be allowed into the United States.
The border official can also check your suitcases and personal possessions, so:
Make sure nothing that you bring appears to contradict your visa status. If you are coming as a tourist, don't bring along a book on how to immigrate to the United States or a stack of job-seeker's résumés. You might have these things simply because you have future plans to apply for immigration, but the CBP won't likely see it that way.
Do not bring illegal or questionable items. It might be legal in your country to carry a firearm (a gun), but it is not legal to bring it into the United States. If you have one in your luggage, it could lead to your immediate removal. Make sure you are not carrying other illegal or questionable items, such as illegal drugs, pornography, or plants, fruits, and animals of types or species that are not allowed into the United States.
For more information on when you can be legally excluded from the United States, see Inadmissibility: When the U.S. Can Keep You Out. And for details on getting a visa, understanding the privileges and responsibilities it comes with, and successfully entering the United States, see U.S. Immigration Made Easy, by Ilona Bray (Nolo).