Most of it, trough the spoils of war. See related questions for further detail.
Mexico
Mexico.
Mexico
Texas borders just one country (besides the US), that's Mexico to the southwest.
No. It is considered as part of the US Southwest.
mexico
Spain had the first claims in the American southwest. Once Mexico gained independence, this area was a part of Mexico. However, the US gained control as a result of the Mexican-American War.
Mexico borders the US along much of the southwest.
New Mexico's Mountains
i think that would be false. I know for a fact that most of the southwest u.s. was part of Mexico.
It is it's own country.
Mexico