Just on a more detailed note in reference between US Citizens and Canadian Citizens crossing any USA-Canada border....
Citizens of the United States are the only citizens permitted to cross into Canada without a passport or official card....However all citizens of Canada and other foreign decents of citizenship must have a passport to enter Canada (or other proper equivelent documentation for Canada Citizens to re-enter Canada).
Citizens of Canada are the only citizens permitted to cross into the United States without a passport or official card....However all citizens of the United States and other foreign decents of citizenship must have a passport to enter the United States (or other proper equivelent documentation for US Citizens to re-enter the United States).
Only citizens of the United States without a passport or official card can be permitted into Canada with the minimum documentation of an official enhanced form of ID and a certificate of live birth showing you were naturally born in the United States (which shows the proof of citizenship requirement).....
Only citizens of Canada without a passport or official card can be permitted into the United States with the minimum documentation of an official enhanced form of ID and a certificate of live birth showing you were naturally born in Canada (which shows the proof of citizenship requirement).....
I believe the privilaged rule here between US and Canadian Citizens with the minimum proof of citizenship requirement to enter each other's country is the fact that Canada has only one foreign country as a neighbor : which happens to be the United States.
Although Mexico is part of the WHTI pact, Citizens of Mexico can only enter the United States or Canada with a passport or official card, same requirement for US and Canadian Citizens entering Mexico.
A passport card for all land, sea, and ferry ports of entry is sufficient to enter or re-enter Mexico, United States or Canada for all citizens of each of these three countries....
However as Sue pointed out should you need to re-enter the United States or Canada upon emergency by air travel, a passport card will not be sufficient to enter either country - you must bear and possess a passport.
One other note for US Citizens is that if you are a naturalized or natural born citizen of the United States, you cannot be denied entry into the United States, however without the official required documentation upon the type of travel arriving at any US port of entry, you will be subject to vigorous additional screening in which US Customs or ICE or TSA would make you wish you had a passport.
In my opinion I think obtaining an official US passport is the best way to go as you will not have requirement troubles entering any ports of call in most world countries no matter which form of travel you use....(Especially if you reside in Alaska).
The US passport card is cheaper and faster to obtain which has the same 10 year validation, however you are restricted from air travel and contained to foreign travel perimeters of Canada, Mexico, Carribean and Bermuda Regions.
Also, it is always a great idea to always check with the CBSA and US State Department websites for the current info prior to destination of your travel as rules and requirements can be subject to change on a moment's notice.
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