The Associated Press

PHOENIX - As federal authorities crack down on immigrant smugglers in Phoenix, smugglers are scattering drop houses in rural communities to avoid detection, immigration officials said.

"The level of enforcement in urban areas has forced smuggling organizations to move to other areas to accomplish their ends," said Russell Ahr, a spokesman for the U.S. Bureau of Immigration and Customs Enforcement in Phoenix.

Drop houses serve as stopovers for illegal immigrants headed elsewhere.

The crackdown started last year made it harder for smugglers to operate in Phoenix, a hub for transporting immigrants to other parts of the country. It also prompted smugglers to move parts of operations to other cities and towns.

In two Sierra Vista cases this month, agents arrested 26 illegal immigrants and accused a city resident of being involved in a smuggling operation.

Arizona became the busiest illegal entry point along the about 2,000-mile U.S.-Mexico border in recent years after tightened patrols in California and Texas pushed more immigrants toward the state.

The federal government began its crackdown roughly a year ago, focusing first on violent smugglers in Phoenix.

"We've seen a noticeable drop in the number of drop houses and a decrease in kidnappings and extortion associated with smuggling," said Phoenix police spokesman Detective Tony Morales.

While Tucson has had drop houses in the past, the number discovered has grown in the last six months, largely because of a tip line for the public to report smuggling operations, said Andrea Zortman, a spokeswoman for the U.S. Border Patrol's Tucson sector.

The number and size of drop houses have gone up in Yuma in recent months, too, with as many as 40 immigrants found at one location.

Several small drop houses have been found in the last couple of weeks, some in older mobile home communities in Yuma, about 20 miles north of the border, said Yuma sector spokesman Joe Brigman.