If you are a U.S. green card holder (lawful permanent resident), the right to travel outside the U.S. and return is one of the privileges that comes with your status. However, that does not mean that your reentry is guaranteed. You will need to take care to bring the proper documents, maintain your U.S. residence, and be aware of the risks of being found inadmissible or deportable upon your reentry.
Even though you are now a U.S. resident, you will need to bring your foreign passport when traveling, for purposes of entering other countries. A U.S. green card is not sufficient by itself as a travel document, though it is enough to get you back into the United States.
You will, in fact, be expected to present your valid, unexpired green card upon reentry to the United States. (This is also known as a Permanent Resident Card or Form I-551.)
If you believe you'll be staying outside the United States for a year or more, you should get a reentry permit before leaving. Please see Reentry Permit Process for U.S. Permanent Residents.
If you don't have a green card yet, you can travel with an I-551 stamp in your passport. Or, if your conditional green card is past its two-year expiration date, you will need to bring the expired card as well as the receipt from U.S. Citizenship and Immigration Services (USCIS) showing that you filed your application to remove the conditions on residence on time, and are awaiting a decision.
If you have applied for adjustment of status or asylum and your application is still pending with USCIS, you will also need to show an Advance Parole document, which indicates that you received permission to travel without having your application cancelled. You may have received this permission in the form of a notation on your work permit (EAD); look for a line saying, "Serves as I-512 Advance Parole."
There is an exception to the Advance Parole requirement, as well: If you still have a valid H-1, H-4, L-1, L-2, K-3, K-4, V-2, or V-3 visa, you do not need Advance Parole to travel abroad after submitting an application to adjust status.
If your green card is lost or stolen while you are outside the U.S., contact your nearest U.S. embassy or consulate. It should be able to provide you with what's called a U.S. Government Transportation Letter, for travel to the United States.
If the green card was stolen, be sure to notify the local police, in order to obtain a police report. This will help you convince the consulate that you are acting in good faith and did not, for instance, sell your card.
When you reach the U.S., the officials at the airport, border, or other entry point may also require you to complete USCIS Form I-90: Application to Replace Permanent Resident Card and pay the appropriate fee. For more information, see How To Complete Form I-90.
If you have been away for more than one year, you will also need either a Reentry Permit or (if you have been away for two years or more) a Returning Resident Visa to reenter the United States. For more information on why you might need one of these and how to apply, see Abandonment of Residence by U.S. Green Card Holders.
Even if you have been away from the United States for less than a year, you can be denied reentry if it appears that you cut ties to the U.S. and made your home elsewhere -- called "abandonment of residence." Although the immigration authorities start to look hard at returning residents after trips of six or more months or more, it is technically possible to abandon your U.S. residence in as little as a day. It's all about your intention when you left.
The customs and border patrol inspectors will look at things like whether you are routinely employed abroad, whether your primary family members are citizens or permanent residents of a foreign country and where they actually live, whether you still have a fixed address in the United States, and whether you frequently spend extended amounts of time outside the United States.
You may remember that, in order to obtain your green card in the first place, you had to prove that you were not "inadmissible" for reasons of health conditions, criminal convictions, the likelihood of becoming a public charge, and so on. Under certain circumstances, these grounds of inadmissibility can be applied to you again, when requesting U.S. reentry. The circumstances (found in § 101(a)(13)(C) of the Immigration and Nationality Act, or I.N.A.) include where you:
A DUI conviction will not usually bar you from U.S. entry. However, if you have any criminal violation on your record, you should not leave the U.S. without consulting with an experienced immigration attorney first.
If you are found inadmissible upon return to the U.S., you may be barred from reentry for a number of years. If it looks like this is going to happen, your best bet may be to withdraw your request for entry, return to where you came from, and consult an immigration attorney before trying again.
If the immigration authorities notice, upon your U.S. reentry, that you have done something that makes you deportable but not inadmissible -- for example, been convicted of one of various crimes -- you may be referred to Immigration Court for removal proceedings. Again, you will absolutely want to consult an immigration attorney under such circumstances.
See our article on deportability and inadmissibility for more on these two sets of laws.