[Verginius Rufus]

The area south of the Arkansas River plus the land west of a line running north from the source of the Arkansas was all part of Mexico until 1848.

There is a map showing when different areas were acquired by the US on Wikipedia at en.wikipedia.org/wiki/United_States_territorial_acquisitions

[mad puppy]

Great Map VR, thanks. I'm just outside of Denver and apparently not in the part they want back. Not that I've lost any sleep on that matter.

Seems like the US paid for the land after the US won the war: $15 M 160 years ago is probably worth more in todays $'s than Mexico's yearly gov't budget. Rather than trying to get it back, maybe they should be thinking about selling us more, though I certainly don't need another time-share.