1906 Mexico 1 Centavo

There were both narrow and wide dates in 1905, 1910, 1911, and 1914 also, with all those supposedly made only in Mexico City, so that doesn't seem like it'd serve as a reliable marker for the Birmingham pieces. One sources I've consulted calls the English and Mexican versions "identical".

I've seen a webpage that asserts that for the 1914 5 centavos the narrow date were minted at Mexico City and that the wide dates came from Birmingham. Supposing that's an established fact, it's tempting to extrapolate on such to include other issues that exhibit both wide and narrow date configurations. I'd point out that there's an underlying assumption that the dies for the coins were made where they were struck, although I guess Mexico could've supplied dies with the other date style to Birmingham deliberately as a "code" that indicated their foreign contract origin. Somewhere in the Mexican government archives the answer may lie, if those records survived the revolutionary chaos of the period.