Whether you traveled by car to Canada to see Niagara Falls, or flew to Vancouver to tour the city, you were required to provide citizenship and identification documents before you could cross the border into Canada. Depending on how you're traveling back to the United States, you'll need to provide much of the same documentation to return to the U.S. after your trip.
Proof Of Citizenship
If you're returning to the U.S. by land, you must provide one Western Hemisphere Travel Initiative-compliant document to prove your citizenship. This includes a valid U.S. passport, passport card, enhanced driver's license, a trusted traveler card such as NEXUS, or a Native American Tribal Photo Identification or Enhanced Tribal Card for Native Americans. Military personnel can also use their military identification along with official orders proving the reason for travel. U.S. citizens on official maritime business can use a U.S. Merchant Mariner document. If you are returning to the U.S. from Canada by air, you can only use a U.S. Passport as proof of citizenship.
Chilren Under 16
If you're traveling to and from Canada with children under the age of 16, you must provide an original or a copy of each child's birth certificate. Other acceptable documents for American minor children include a Consular Report of Birth Abroad and a naturalization certificate. Children don't need a U.S. passport for this trip. If you're traveling with your kids without their other parent, or if you're traveling with kids that are not your own, you must have a signed, handwritten letter from the non-traveling parents, giving you permission to travel to and from Canada with the children.
Native American Exception
As of publication, the Department of Homeland Security is working with all U.S. federally recognized tribes to produce an Enhanced Tribal Card, which will make it easier for Native Americans to cross in and out of the Canadian border by land. In the meantime, Native Americans can continue to use either their Native American Tribal Photo ID, Form I-872 American Indian Card for Texas and Oklahoma Kickapoo Americans, or an Indian and Northern Affairs Canada Card.
Cruises and Boats
If you're returning from Canada to the U.S. via a cruise ship that departed from the U.S., stayed within the Western Hemisphere and is returning to the same U.S. port, you may present any government-issued photo ID along with proof of citizenship, such as your passport, birth certificate, naturalization certificate or Consular Report of Birth Abroad. Always check with your cruise line to make sure you bring all required documents. For passengers traveling from Canada to the U.S. on a ferry or other small boat, the same rules apply as if you were crossing by land; you must provide any Western Hemisphere Travel Initiative-compliant document as proof of citizenship.
If you are returning to the U.S. by air, you will be handed a U.S. Customs and Border Protections Declaration Form, requiring you to declare anything you purchased in Canada that you are bringing back to the U.S. This includes anything that was given to you as a gift or items you are bringing back for someone else. You must also declare all the money you have on you. Certain items will be restricted or prohibited altogether, including some alcoholic beverages, firearms, biological specimens and certain animal products. Most goods purchased in Canada are considered duty-free or eligible for a reduced duty rate due to the North American Free Trade Agreement. If you are traveling by land, when you arrive at the border a CBP officer will ask you what you are bringing back with you. Depending on how much you're carrying, he may ask you to fill out a declaration form. Be aware that your luggage may be searched.