AMERICAN AUTO MAKERS USING MORE MEXICO ASSEMBLY LINES Published: New York Times, July 25, 1982, Iver Peterson NOGALES, Mexico, July 18 - Detroit's automobile companies, like other American manufacturers, are setting up an increasing number of plants in border towns like this one where American-made materials are assembled into finished products by inexpensive Mexican labor. The goods assembled in these plants, which the Mexicans call maquilas, are then brought back to the United States under special low tariff rates. As the United States recession has deepened and some 10 million Americans, including a quarter-million auto workers, have lost their jobs, the number of employees in the maquilas grew to 128,000 by June 1981 from 91,000 in 1979, a 40 percent increase. The number of plants, meanwhile, grew from 459 to 604, according to the Commerce Department's latest figures. Calculators, clothing, suitcases, sunglasses and a host of other items requiring hand assembly flow from the plants back into the United States, with automotive components and subassemblies a growing part of the total. General Motors opened its first border plant in Ciudad Juarez in 1979, and began hiring for its 10th one, there and elsewhere, a few weeks ago. It now employs about 5,300 Mexican workers. They assemble wiring harnesses, motor magnets, turn signal stalks and numerous other auto components. Ford, making interior trim, employs 180 at its plant in Ciudad Juarez. Chrysler, assembling wire harnesses, also has an 800-employee operation there. And American Motors, through its subsidiary, Coleman Products Inc., joined Caterpillar Tractor, Samsonite luggage and Foster Grant sunglasses, among others, here in Nogales last March when it hired its first crew of young Mexican workers to cut and wrap wiring harnesses. American labor unions have attacked these operations as ''runaway plants'' that are no less exporters of United States jobs than the foreign imports that American corporations have appealed to Washington to curtail. ''There was no great need for them to cut the corner on the dollar as long as times were good,'' said Rex Hardesty, the A.F.L.-C.I.O.'s Washington spokesman. ''But they make a grab for the coolie wages as soon as things get tight and it become cost-effective for them to do so.'' But the corporations contributing to the boom in maquilas, an untranslatable term whose root is Spanish for ''machine,'' argue that American labor costs are out of line with world competition, that many Americans will not perform the tedious, unskilled handwork to which the maquilas are limited by law, and that the Mexican plants provide an outlet for American materials while aiding Mexico's economy. ''We have observed over the past five years that the cost of our products were becoming less competitive in the world market,'' said James Tolley, a spokesman for American Motors, expressing a view similar to that of other auto makers. ''We therefore established a strategy to continue to operate U.S. plants, but to expand in Mexico to average our cost downward.'' Refusal to Disclose Wages American Motors refused to disclose the wage rates at its plant here, terming the information a ''proprietary'' secret. But employees of Coleman Products de Mexico, interviewed on their lunch break at the Parque Industrial a few miles south of here, said they received 2,400 Mexican pesos, about $50, for a 48-hour week, which works out to slightly more than $1.04 an hour. American Motors also refused to disclose pay levels at its two Coleman Products plants in the United States, in Coleman, Wis., and Iron River, Mich. Both plants, in small, rural towns, have twice rejected affiliation with the United Automobile Workers, whose members in manufacturing jobs earn upwards of $12 an hour and whose benefits add another $8 an hour to that. Company officials insisted that the Mexican plant did not take United States jobs because its two plants there were operating at capacity. The maquilas operate under strict regulations on both sides of the border. The Mexican Government allows the United States company to import, tax-free, the machinery and raw material needed to perform the work, provided that the finished product and everything else, including the machinery and even packing crates, is eventually reexported to the United States. The Tariff Exemptions United States tariff regulations, meanwhile, exempt these imported products from all duties except for the value of the Mexican labor added to it. In 1978, the last year for which the Commerce Department has assembled the figures, this amounted to $12.7 billion. Mexico is the main location for such operations by United States companies, but the system also operates extensively elsewhere, including the Carribean, where American-woven and cut fabrics are sewn into clothes. The legislative principles behind the duty exemptions for all but the value of labor added outside the country date from the 18th century in United States tariff law. They hold that materials whose production has already been taxed at its origins in the United States should not be subject to new levies upon being brought back after assembly or finishing abroad. Mexico encourages the plants because they reduce this country's enormous pool of surplus labor at minimal but decent wages by local standards. Payroll Taxes Aid Cities Through payroll taxes, the plants, meanwhile, pay local taxes that in Ciudad Juarez, where most of the plants are situated, amount to more than half of all city receipts, according to studies done at the University of Texas at El Paso across the border. Besides Ciudad Juarez and Nogales, the plants also operate in Matamoros, opposite Brownsville, Tex.; Nuevo Laredo, across from Laredo, Tex., and Tijuana, below the California line. ''They may be taking some money out of the pockets of workers in Lorain, Ohio, and Detroit by putting more jobs down there,'' said Prof. Ellwyn R. Stoddard of the University of Texas at El Paso, ''but they put it back into the American communities and in other workers' pockets by providing an outlet for the materials the maquilas use.'' It has also been argued that the maquilas reduce illegal Mexican emigration by providing jobs south of the border, although Professor Stoddard and other experts on the maquila system dispute this on the ground that most of the workers in the plants are women, while most of the illegal aliens crossing the border are men. Some Critics in Mexico The system has its critics among Mexicans, too. A study by the Center for Third World Economic and Social Studies in Mexico City speaks of the disruption of traditional Mexican family life because most of the plants' work forces are young women, lured to the border by jobs paying five times the going rate for unskilled labor in the local economy. Perhaps for these reasons, the American corporations are sensitive to charges of exploitation and appear glad to operate under a system of considerably greater secrecy that is normally possible in the United States. The manager of Coleman Products de Mexico, the American Motors subsidiary, refused to let a reporter inside his plant, describing what goes on there, like the wages paid, as ''proprietary.'' Xavier Partidas, a foreman at the new Coleman plant, spoke willingly, however. ''We have all women, 98 percent women, on the assembly line,'' he said as he stepped out for a breath of fresh air the other day, ''and the biggest problem for them is the standing up. I think they are happy to work there but they do not like the standing, so we are always getting a rotation of workers.'' But jobs in the maquilas are eagerly sought. Rosa, the only name she offered, a woman who said she was 22 years old, said that before she went to work for Coleman Products, the only job she had found had been repacking the tomatoes that stream through Nogales to the United States late each winter. The pay was ''poco, poco'' - very little. ''They treat us very well,'' she said. ''It is a very good job except that we have to stand up all day, and we can only go to the washroom when our turn comes. But I have never had a good job like this before.''