MEXICO CITY -- A daylong protest dubbed "A Day Without Gringos" drew thousands of Mexicans into the streets Monday and kept many away from U.S.-owned supermarkets and fast-food restaurants to support rallies in the United States. Some Mexicans said staying away from U.S. businesses was tough, and customers streamed into some branches of Wal-Mart, McDonald's and Burger King in Mexico City. Wal-Mart shopper Juan Ortiz, a 28-year-old salesman, said he supports legalizing migrants, but didn't think it was practical to boycott U.S. goods. "You have to buy what is least expensive here, and I have to buy things for my...