GREEN VALLEY, AZ – JULY 31: A cow skull, probably hung by an immigrant smuggler, points the way up a backcountry trail into Arizona from Mexico on July 31, 2010 near Green Valley, Arizona. Immigrant aid groups and law enforcement alike say that the number of immigrants crossing illegally into Arizona from Mexico has slowed dramatically in 2010, with jobs scarce due to the U.S. recession and widespread fear in the Latino community associated with Arizona’s new immigration enforcement law SB 1070. (Photo by John Moore/Getty Images)
