Two things grant the long-term rights to live and work in the United States: Citizenship, which is received at birth or granted by naturalization, or lawful permanent resident status, which is demarcated by a special ID card, colloquially known as a green card. U.S. passports and passport cards are available only to citizens of the U.S., but having a green card does get you a step closer on the path to citizenship, and it also offers many of the other rights of U.S. citizenship, including reentry to the United States under certain conditions.
How You Can Travel With a Green Card
Although a green card doesn't entitle you to a U.S. passport, it does mean that you can come and go freely from the United States and U.S. territories like Puerto Rico. There are a few conditions attached to absences of more than six months. If you're out of the country for more than 180 days, you're subject to the same inspection procedures as new immigrants when you return. If you're gone for more than a full year, you must present a reentry permit when you return. And if you're out of the U.S. for more than two years, you'll need a returning resident visa to re-enter the country.
One small perk of traveling on a green card instead of a passport: You don't have to fret about having a passport that remains valid for several months past your planned travel dates. Your green card just needs to be valid on the day you enter the U.S.
Going to and From Canada
If you're visiting Canada by land or sea (for example, driving or on a cruise ship or ferry), you don't need a passport at all – your green card is sufficient proof of your identity and your lawful permanent resident status in the U.S. If you're flying to Canada, however, or even passing through one of its airports, you do need an electronic travel authorization. And that, in turn, requires you to have a passport from your country of origin. If you're granted an electronic travel authorization, you'll need to present at the airport both your U.S. green card and the passport you used to apply.
Traveling to Other Countries
As with reaching Canada by air, you'll need a passport from your country of origin to enter most other countries. Often, that means carrying both your passport and your U.S. green card when you travel; you'll use your passport to enter the other country, then your green card to return to the United States. Entry requirements are set by each country; the easiest way to verify which documents you'll need to enter is by contacting your destination country's embassy or consulate.
Aside from easy reentry, your green card entitles you to another set of rights in the U.S. These include confirming employment eligibility, applying for a Social Security card, getting a state-issued driver's license, petitioning for certain family members to join you in the United States and voting in state and local elections.