One way of comprehending the Mexican problem of poverty and the urge to jump across the American border is to look at minimum wages.

In the Federal District (Mexico City), the daily minimum wage is 120 pesos, or about $5.30 at present exchange rates. The minimum is slightly higher in northern industrial districts, and drops as low as 57 pesos, or about $2.50, in Palenque, in the Chiapis district.

But as low as these daily minimum are, the cruelest economic fact of all is that fewer than 50 percent of employers in the urban areas actually pay the minium scale, and non-compliance runs as high as 80 percent in rural areas, according to reliable sources. "Even if you take the theoretical top minimum, the daily wage is less than a Mexican can earn in an hour in the United States," says a nongovernment official. As a result, an estimated 800,000 Mexicans - or roughly the equivalent of the annual addition to the potential labor into Southwestern U.S. states each year.

On both sides of the border, there is agreement that this "safety valve" cannot stay open indefinitely. But no one has conclusive answers. "Mexico lives inperpetual fear that the U.S. will close its borders, or round up the illegal aliens and return them," says an authoratative source.horatative source.