By Mary Lou Bonsack. Oneof the biggest people movements of this century is taking place on the border between Mexico and the United States. This 2,000 mile border separates one of the wealthiest countries in the world and one of the poorest. Dramatic changes are taking place on this border. “Maquiladora,” a Mexican term for “production-sharing” factories, is now a common term heard along this stretch of land between Brownsville and San Diego. American and foreign companies are building factories known as maquila plants. This program began in 1965 as a way to combat Mex