The United States-Mexico border seems to operate like a big, leaky dike. As soon as the US Border Patrol stops one stream of illegal aliens, another one - perhaps hundreds of miles away - opens up.
A stream is flowing in Nogales, Ariz., after stepped-up enforcement reduced illegal entries in El Paso, Texas, and San Diego, Immigration and Naturalization Service (INS) border agents say. Arrests in El Paso and San Diego are down by a combined 83 percent since last fall, according to agency statistics. But arrests in the Tucson sector, which includes the entire Arizona border except Yuma, are up by more than 60 percent in the same period.
Last month, agents arrested more than 10,000 aliens in Nogales alone. The border runs right through downtown Nogales, with Arizona on one side and the state of Sonora, Mexico, on the other. ``Word has gotten around in Mexico that it's easier to get through here,'' says Steve McDonald, spokesman for the Border Patrol's Tucson sector.
``We're seeing more people from [the Mexican states of] Chihuahua and Baja California, who would normally cross other parts of the border,'' Mr. McDonald says. ``We're also seeing more frequent, sophisticated, and larger smuggling operations.''
Mexican activist Teresa Leal from Nogales, Sonora, says she also is alarmed at the desperation of people coming from southern Mexico. ``It used to be, they would have a little money to be able to stay a few days, look around, case out the border, maybe get a job. Now they have no money, and they want to cross right away.''
The shift in the migrant flow has prompted complaints from Arizona leaders that the US lacks an overall enforcement strategy. Critics point out that, while San Diego is slated to get 300 more Border Patrol agents this year and El Paso 50, the Tucson sector will receive only 33 support personnel and no new agents.
But Doug Mosier, a spokesman for the INS in Washington, says his agency, which oversees the Border Patrol, is not ignoring Arizona.
``This is only the first phase of our trying to take control,'' Mr. Mosier says. The agency remains focused on California and Texas because, he says, the majority of the nation's illegal entries still take place in those two states.
South of San Diego, arrests have been reduced by construction of a 14-mile fence of steel mat and the installation of five miles of stadium lights. In El Paso, a Border Patrol operation called Hold the Line has been credited with a massive decline in arrests. The strategy's success has elicited calls from the mayor of Nogales, Ariz., among others, for a similar policy there.
But McDonald says the El Paso operation would be difficult to duplicate in Nogales. ``In El Paso, the river acts as a natural buffer, the land is flat, and they have a road running all along the levee,'' he says. The land around Nogales, in contrast, has steep hills, deep gulches, few roads, and no river.
Although plans have been made to build a two-mile steel-mat wall through downtown Nogales, funding is not expected before next year, and McDonald says he doesn't know when construction will begin. So for now, Nogales agents must rely on fences, cameras, and sensors to stem the tide.
``Also, if we stood along the fence, we'd get rocked,'' McDonald says, referring to the increasingly frequent rock-throwing incidents in Nogales. The rocks are apparently being thrown by youths from Nogales, Sonora, who stand by holes in the fence and charge people who want to enter the US.
Although thousands of miles of border remain essentially open, McDonald says migrants prefer to cross in populated areas because it is easier to blend in and not as dangerous as crossing in the countryside, where they may get lost, die of thirst in the desert, or be set upon by bandits.
Moreover, stiffer border enforcement may have the unintended consequence of increasing the resident illegal alien population in the US. In El Paso, some residents say migrants who used to cross daily to work have decided to stay in the US permanently because it is too hard to get through the blockade.
Leal and others believe the US should expand its guest worker program to give more Mexican laborers the right to work here on a seasonal or migratory basis. ``The solution to this problem is political, not judicial,'' Leal says.