At the border checkpoint in this bustling town, diesel exhaust thickens the air as a dozen Mexican trucks await safety inspections. Those that make the grade rumble through the sun-scorched streets, their goods to be unloaded at nearby warehouses.
Some of the rigs are loaded with tomatoes and melons. Others tote electronic products assembled at US-owned plants south of the border.
Whatever their business, these trucks - as long as Congress gets its way - can't go more than 20 miles north of the border. That rule is just fine with many locals, because the captive trade has been quite lucrative, and the semis themselves haven't caused many safety problems.
Under the North American Free Trade Agreement (NAFTA), Mexican trucks are supposed to have free passage throughout the United States. But that has not been the case. In 1995, the Clinton administration imposed the 20-mile limit and other restrictions. Earlier this month, when Congress voted to continue the restrictions, the townspeople of Nogales received a gift: a guarantee, however temporary, that their economy would keep on truckin'.
"The economic issue is very important, because we have from 80 to 100 warehouse facilities that are used by Mexican trucks on a daily basis, and that local people own and operate," says Nogales Mayor Marco Lopez Jr. "So the economic impact would be tremendous if the trucks were to bypass us."
These concerns ripple up and down the 2,100-mile US-Mexico border, in other towns where trucks are the economy's lifeblood. Taking a closer look at Nogales - at how economic and safety concerns are playing out on the ground - provides clues for what may lie in the trade road ahead.
In the winter produce season, as many as 1,000 trucks enter this Arizona outpost a day, forming a line that can snake two, three, even four miles long. During the summer, the number of diesels drops to about 700, but that's still enough to keep the inspectors busy.
Safety issues, indeed, were a driving force in the recent congressional ban. Citing unfavorable inspection statistics, some lawmakers and union leaders argued that Mexican trucks pose too great a danger to be allowed greater access to US highways. President Bush has said he may veto the ban.
Even in Nogales, folktales about the trucks abound - like the one about a teenager caught driving his rig from atop a milk crate and a stack of phone books. But in reality, Nogales's 20,000 residents have little fear for their safety.
"We see Mexican trucks on our streets every day," says Susan Clarke Morales, executive director of the Nogales-Santa Cruz County Economic Development Foundation. "We do kind of a dance around them, but I think the drivers are pretty safe."
In fact, Mexico's long-haul trucks, which would be deployed if the US ban were lifted, are both newer and better-maintained than the aging fleet of short-haul trucks that currently make the trips across the border.
At a dock in the border inspection complex, Paul De La Ossa looks over a truck whose faded paint has all but erased the company name. As the officials go over brake, exhaust, and electrical systems, an air-brake leak turns up. "If [anything] doesn't meet our standards, the trucks must be towed to a repair shop before they can go back on the road," says Mr. De La Ossa, acting port supervisor for the US Department of Transportation.
Arizona's Department of Public Safety keeps six inspectors at the port, according to Lt. Mike Lockhart. He says about 35 percent of Mexican trucks, most of which are short-haul, fail inspections. That's compared with 25 percent for all US trucks, both long-haul and short-haul. When just US short-haul trucks are considered, the failure rate rises as high as 45 percent.
"Although 35 percent may sound high, there is not going to be carnage on the highways [if restrictions are lifted]," says Lieutenant Lockhart. "While I can't tell you what the accident picture is, I don't know that any [Mexican trucks] have had collisions with American drivers."
Nor do experts believe that US roads will be clogged with Mexican trucks if restrictions are lifted. Just 2 percent of Mexican trucking companies have applied to do business in the US since NAFTA passed in 1994. It's just too expensive for all but the largest to take advantage of.
And Ms. Clarke Morales doesn't see all trade bypassing Nogales, even if Mr. Bush vetoes the ban. "It's not very feasible for the produce industry to make a change, because they own a whole lot of buildings and other facilities here. They already have a whole infrastructure in place."
Lee Frankel, president of the Nogales-based Fresh Produce Association of the Americas, says the impact of liberalized truck travel would be negligible for association members, who ship $1.2 billion in fruits and vegetables through Nogales annually. "From a business perspective, a lot of the political jockeying is fairly irrelevant to the actual trade itself," he says. "The issue has just involved a lot of fear-mongering, and delays in coming up with real solutions for taking truck safety to a better and higher level."
Already, Mr. Frankel says, a few produce brokers have gotten around restrictions by switching to American drivers at the border port and using dual plates - US and Mexican on the tractors, and US on trailers.
For some, the biggest worry is that the Mexican truck debate itself will slow NAFTA's momentum. Mexico has expressed outrage at the bans passed by Congress, and President Vicente Fox has threatened to curtail the number of US trucks allowed to head south. "The border economy has been doing very well up until now," says Dr. Boris Kozolchyk, executive director of the National Law Center for Inter-American Free Trade in Tucson. The truck impasse "will hurt investments in the region.... It is a projected growth that will not take place as a result of there being a lesser amount of traffic coming from and going to Mexico."