Canada and Mexico
Mexico and Canada.
To fly into Mexico you HAVE to have a passport. As of right now the only way you can get into Mexico without a passport is by land travel, but that will change as of Summer 2009. As of Summer 2009 you will need a passport for any land travel into Mexico and Canada.
Canada
Mexico and Canada
Canada in the north and Mexico in the south have land borders with the US.
Canada and Mexico
Canada is larger than both the US and Mexico.
The states that have a land border with another country are Alaska (Canada), Maine (Canada), Washington (Canada), Michigan (Canada), Minnesota (Canada), North Dakota (Canada), Montana (Canada), New York (Canada), Vermont (Canada), New Hampshire (Canada), Arizona (Mexico), California (Mexico), New Mexico (Mexico), and Texas (Mexico).
Canada
The only two countries with land borders with the US are Canada to the north and Mexico to the south.
Canada and Mexico are the two countries that share a land border with the United States.