Into the Beautiful North, by Luis Alberto Urrea. Here's a brief summary, via Amazon:
Nineteen-year-old Nayeli works at a taco shop in her Mexican village and dreams about her father, who journeyed to the US when she was young. Recently, it has dawned on her that he isn't the only man who has left town. In fact, there are almost no men in the village--they've all gone north. While watching The Magnificent Seven, Nayeli decides to go north herself and recruit seven men--her own "Siete Magníficos"--to repopulate her hometown and protect it from the bandidos who plan on taking it over. Filled with unforgettable characters and prose as radiant as the Sinaloan sun, Into the Beautiful North is the story of an irresistible young woman's quest to find herself on both sides of the fence.