(AP) Arrests of people entering the United States illegally along the busiest stretch for such crossings fell for the second year in a row, possibly reflecting economic conditions in both the U.S. and Mexico, a Border Patrol spokesman said Friday.

From October 2007 through August, agents in the 260-mile Tucson sector arrested just under 300,000 illegal immigrants. That's 16 percent fewer than the nearly 359,000 caught during the same period last year.

In the 125-mile Yuma sector, fewer than 8,000 illegal immigrants were captured in the same period - down from more than 37,000 last year, for a 78 percent decrease.

"There are a number of different elements for any change, including, of course, our right mix of man power, technology and infrastructure," Tucson sector spokesman Rob Daniels said.

National Guardsmen supplemented the Border Patrol until July. The now-completed two-year mission deployed as many as 6,000 Guardsmen along the entire southwestern border as the patrol launched a hiring program to double its number of agents.

The Guard's presence in a variety of roles allowed the Border Patrol "to be more of a deterrent," Daniels said. "The intent was to prevent the crossings, to prevent the deaths from occurring."

The number of illegal immigrants who died in Tucson sector deserts also dropped by 20 percent, from 193 to 154, from October 2007 through August.

Added Border Patrol agents, fencing and other infrastructure like powerful lighting, observation towers and improved roads all have helped reduce apprehensions by making it tougher to cross into Arizona, Daniels said.

But he added, "Obviously, the economy in both the United States and Mexico is always a factor."

With the economic downturn, fewer jobs have been available for illegal immigrants, particularly in fields such as construction, he said.

And employer sanctions enacted by the Arizona Legislature have dissuaded the hiring of illegal immigrants, Daniels said.

"It's removing the draw, the attraction, and then our enhanced enforcement operations have tried to ... break the smuggling cycle," he said.

Tucson sector Chief Robert Gilbert said in a recent interview that several programs to return prosecuted or apprehended illegal immigrants to Mexico are designed to sever reconnection with the smugglers who brought them across the border.

One program buses prosecuted immigrants to border crossing points far from Arizona; another returns 266 people a day by plane to Mexico City.

The patrol can't track how many people successfully enter the country, Gilbert said, but it does its best to monitor entries, "and what we're seeing is a larger decrease in entries, as best we track it, than we are a decrease in apprehensions, showing a higher level of effectiveness."

© MMVIII The Associated Press. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed.