Existing comment:
One of Mexico's Rarest Stamps:
Victoriano Huerta seized Mexico's presidency in 1913, and the state of Sonora became a stronghold of northern opposition forces led by Alvaro Obregon. Revolutionary postage embossed with the word Constitucional demonstrated Sonora's anti-Huerta sentiments. This example, one of two known unused copies of this variety, is among Mexico's rarest stamps.
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