I bought a lot of covers and found this one from Aguascalientes district, sent to Zacatecas, dated July 1st 1879 and signed in "Las Pilas" with a difficult to read cancel. I checked Peter Taylor's book and it looks like Villa de Calpulalpan cancel AG-3/1, wich is described as seen in official post office publications or museum collection, but not on an actual stamp.
Did I get a rare one? Any comment?
Best regards,
Eugenio.