<P> In Mexico, a maquiladora (Spanish pronunciation: (makilaˈðoɾa)) or maquila (IPA: (maˈkila)) is a manufacturing operation, where factories import certain material and equipment on a duty - free and tariff - free basis for assembly, processing, or manufacturing and then export the assembled, processed and / or manufactured products, sometimes back to the raw materials' country of origin . They are an example of special economic zones as seen in many countries . </P> <P> In 1964, the Bracero Program, which allowed Mexican agricultural workers to work legally in the U.S. on a seasonal basis, came to an end . Less than a year after the end of the Bracero Program, the Mexican Government launched the Border Industrialization Program (BIP) or the Maquiladora Program, to solve the problem of rising unemployment along the border . The maquiladoras became attractive to US firms due to the availability of cheap labor, devaluations of the peso and favorable changes in US customs laws . In 1985, maquiladoras overtook tourism as the largest source of foreign exchange, and since 1996 they have been the second largest industry in Mexico behind the petroleum industry . </P>

What type of factories are in mexico that assemble imported materials