When traveling on Greyhound to Canada or Mexico, a passport is generally required for entry into those countries. Greyhound's services include cross-border routes, and travelers must adhere to the regulations of the country they are entering. A valid passport is essential for identification and necessary documentation when crossing international borders. In addition to a passport, travelers may also need to provide other forms of identification or meet specific entry requirements set by the destination country. It is advisable to check the latest travel requirements on the current Greyhound website or other official resources prior to your trip. This will ensure that you have all the necessary documentation and are aware of any potential visa requirements based on your nationality.