The railroad connection stands out, because I am retired from a railroad too. I worked on the Boston Subway system before I went to law school. I should have done all this research when when My tios and tias were still alive. I have seen Rodolfo Fierro's picture on Winikiepedia (Or whatever they call it!), and he look like me when I was around thirty or so - strange! And Rodolfo Fierro also worked on a railroad! It's hard to establish a connection because so many of my older relatives have passed away.
I don't know if we are related to General Roberto Fierro,
who was the governor of Chihuahua, who helped found the Mexican air force, and who flew non-stop from New York to Ciudad Chihuahua in the nineteen thirties. His record stood for many years. I have never seen a picture of General Fierro.
In all of Spain, there are only 2300 people with the surname of Fierro, though some may spell it with an s, as your family does. Some have kept the old castellano spelling of "Hierro". I have never met another latino person with this surname. There is a large economic consulting group in Madrid named "Gruo Fierro".
I have one tia who is still alive, but she is over ninety, and her memory is not good. I will try to see what she remembers about my grandfather.
Robert H. Glotzer (y Fierro)firstname.lastname@example.org