Before you arrive in Canada, you may be asked to complete a Customs Declaration Card. Complete this card before meeting with customs and immigration officials, even if you aren't a Canadian citizen. If you're traveling by air, it's a good idea to complete the card before you leave the airplane.
In addition to your passport, you may need a travel authorization such as a visa or an Electronic Travel Authorization (eTA) to enter Canada. Consult Immigration, Refugees and Citizenship Canada's website to learn which authorization you need: Find out if you need a visa to travel to Canada.
Who already have a visa in their passport. Travelers may wish to avoid buying plane tickets until they have obtained an ESTA (or a valid visa, in case the ESTA is not approved). ESTA applications may be submitted at any time prior to travel. The processing of an ESTA can take up to 72 hours.
If you don't have one, you won't be able to board your flight.
American citizens, including American-Canadian citizens, must carry proper identification and meet the basic requirements to enter Canada. You do not need a Canadian passport, a Canadian visa or an eTA to enter Canada if you are travelling with a valid U.S. passport.
You do not need an eTA , if you are: arriving by land and sea – you must have acceptable travel documents and ID. a British-Canadian dual national – you must have a valid Canadian passport.
The airline staff will scan your passport to confirm that you have a valid eTA. If you don't have one, you won't be able to board your flight.
When you travel to Canada make sure you have: your letter of introduction. valid passport or travel document. if you're visa-required, it must contain the visa sticker that we put in it. if you need an eTA and you're flying to a Canadian airport, it must be the passport that's electronically link to your eTA.
ETAs can also be obtained via smartphone or tablet. This means that if a traveller has forgotten to obtain an eTA, they will be able to do so at the airport. However, it is strongly recommended that eTAs be obtained at least 72 hours before booking any travel.