No. Mexico is a sovereign nation. There are treaties between the countries, but Mexico is not a protectorate.
US involvement into Mexican internal affairs strained the relationship between the countries.
Rio Grande. *is from Texas*
The main countries that border the US are Canada, and Mexico.
Mexico and Canada.
Canada and Mexico.
Mexico
Yes. Both countries have extradition treaties between each other.
They don't. There aren't any passenger lines between the two countries.
Canada and Mexico
Canada, Mexico
The US, Mexico and perhaps Cuba.