It has been both ways.
Share a common border.
None. Mexico's border touches New Mexico's state limit (and US border).They share a common border.
Mexico
Canada and Mexico share a border with the United States.
True. Canada and The United States share a border to the north of the US, and Mexico and the US share a border to the south of the United States (US).
Canada and Mexico
Canada and Mexico are the two countries that share borders with the United States.
Canada and Mexico share borders with the United States.
California, Arizona, New Mexico, and Texas are the US states on the border with Mexico.
Mexico and Canada
They share a common border.
US states that border Mexico, from west to east:CaliforniaArizonaNew MexicoTexasThe only US state that borders the Caribbean Sea is Florida, but it doesn't border Mexico.