In recent years there has been a flurry of bi-lateral trade deals between countries and the emergence of regional trading blocs. For example, the European Union now has over 30 separate international trade agreements including those with countries such as Colombia and South Korea.
Since 2008 all US citizens MUST have a US passport to be allowed to enter the United States. If your aunt travelled to Jamaica with just her US naturalisation certificate, she would not be able to board her plane back to the US. She would have to come to the Embassy to apply for a passport in order to return home. Issuing a new passport takes at least a week, so this could extend her holiday much longer than she had planned. The good news is that she can apply for a US passport before she leaves the United States.
If you are a US citizen, you can indeed cross into Canada using your birth certificate and a photo ID. For safety reasons, you may want to bring the original birth certificate, or at least a certified copy.If you are not a US (or Canadian) citizen or permanent resident, you cannot enter Canada without passport:or safety reasons, you may want to bring the original birth certificate, or at least a certified copy. If you are not a US (or Canadian) citizen or permanent resident, you cannot enter Canada without passport: