Porous U.S.-Mexico Border Stretches Across Arizona

NOGALES, AZ - MAY 02: U.S. Border Patrol vehicles move near the border fence between the United States and Mexico on May 2, 2010 in Nogales, Arizona. Although the U.S. government has spent billions of dollars constructing border defenses in the last decade, critics say that Arizona's border with Mexico was left with less protection, compared with California and Texas. Proponents of Arizona's new immigration enforcement law say that federal inaction led to passage of the new law, which has raised fears of racial profiling by police against Latinos. (Photo by John Moore/Getty Images)