Here's an email I received today:

Hi Joe,
Who owns the copyright to music and words to Chiapanecas? I would like to use it in a piano book for children.
Thanks,
Karol

This is one of those tunes I've known since I was young, so the temptation is to say that the tune is traditional and in the public domain. But Wikipedia says the "Chiapanecas" melody was composed by the musician Bulmaro López Fernández (1878–1960). Since 1923 is the general cutoff date for public domain, it isn't so clear. And most likely, all English translations of the song were written after 1923.

The Harry Fox Agency Songfile utility lists lots of versions of "Chiapanecas" that you can pay royalties for, but there's no information I can find that gives definitive information about ownership of this song.

I'm more-or-less of the opinion that if a song has been around since 1950 and the history of ownership is cloudy before that, it's best to act as if the song is in the public domain - knowing that there is a slight chance that somebody will place a claim against you.

I don't think one can prove ownership of this song, one way or another.

-Joe-