Becky,you got me curious, so I looked it up. "Ten-gallon hat" is the result of a linguistic mix-up. "Galón" is the Spanish word for "braid." Some vaqueros wore as many as ten braided hatbands on their sombreros, and those were called "ten galón hats." English speakers heard gallon. Real cowboy hats came to Texas from the Spanish via Mexico (unless you want to go all the way back to Genghis Khan and the Mongolian horsemen, who apparently wore something similar).