Pedro Aguirre & Co., black company frank on unused 1884, 2¢ brown on amber entire, Very Fine, this is believed to be the only known mint example of this frank. Scott No. U278  Estimate $1,000 - 1,500. In 1873 gold was discovered south of Arivaca near the Mexican border which led to a Gold Rush in that area. This led Pedro Aguirre in 1877 to start a route from Tucson to Arivaca and then south to the Oro Blanco mining camp. This continued until he sold the company in 1886 and retired. $0 (Image)