TUCSON, Ariz. (AP) — U.S. Customs and Border Protection is pushing to ease a staffing shortage at Arizona-Mexico ports of entry that business leaders say is hurting the state economy by causing lengthy waits for trucks and tourists.

The agency has struggled to attract new officers for its Office of Field Operations since announcing more than a year ago that it had been allocated 170 new positions in Arizona.

On Monday, it participated in a job fair organized by Tucson Mayor Jonathan Rothschild to find candidates.

The staffing shortage is especially acute in Nogales, the closest port of entry to Tucson and part of a crucial trade corridor between the U.S. and Mexico.

Trucks carrying fruit, vegetables and other products from Mexico endure backups as they wait for the dwindling number of customs agents to search vehicles for marijuana, methamphetamine and heroin that smugglers often try to sneak into the U.S. from Mexico.

"Customs has a unique position where their jobs create other jobs in the United States. It drives kind of our economic engine," said Allison Moore, the director of legislative and regulatory affairs for the Fresh Produce Association of the Americas. "They just need enough people to do that efficiently."

Customs and Border Protection announced in May 2014 that it was filling a total of 2,000 new positions in the Office of Field Operations. Of the 170 new jobs allocated for Arizona, 120 are to be assigned in Nogales, the state's busiest area for crossings.

But 18 months later, none of those positions has been filled, and Nogales is down 50 officers due to attrition. That puts Arizona at a 20 percent shortage of staff.

William Brooks, director of field operations for the Tucson field office, said the agency is allocating overtime and using staff around peak travel times. Hiring is a challenge partly because the agency has a high standard for new hires, he said. Entry level officers can make between $32,000 and $48,000 a year.

"Typically it takes a lot of applicants for us to get one person to bring on duty," Brooks said.

A bill introduced by Republican U.S. Sens. John McCain and Jeff Flake and signed into law helps speed the hiring of military veterans for such positions.

Michael Hamilton, a 28-year-old graduate of Northern Arizona University who studied criminal justice and works as a debt collector, said he was considering applying after speaking with a recruiter at the job fair.

"It seems like it's a job where there's a lot you can do," Hamilton said as recruiters and high-level officials mingled and handed out flyers, whistles and other items while encouraging visitors to apply on the government website.

Bruce Bracker, treasurer of the Greater Nogales Santa Cruz County Port Authority, said Nogales ports of entry for passenger cars and pedestrian also have notoriously long wait times. Many Mexicans who typically do their shopping in the U.S. no longer want to make the trip, he said.

The newly renovated Mariposa Port of Entry, which has eight commercial lanes and 12 for passenger vehicles, has helped, but problems persist, Bracker said.

Mexican tourists spend about $2.6 billion in Arizona each year, according to the Arizona-Mexico Commission.

"We know it could be much better," Bracker said. "Why don't we want those tax dollar for our city, our county and our state?"