In Oct. 2006, the U.S. government decided to build a 700-mile fence along its troubled 2000-mile-plus border with Mexico. Three years, 19 construction companies, 350 engineers, thousands of construction workers, tens of thousands of tons of metal and $3 billion later, was it all worth it? When Arizona recently enacted one of the most extreme immigration laws in the country, the Obama administration responded by filing a lawsuit against the state. This dispute was merely the latest symptom of a greater national problem: the lack of a comprehensive, workable U.S. immigration policy. In its place, lawmakers have resorted to a series of half-measures, the most expensive of which — the U.S.-Mexico border fence — extends through the desert 150 miles south of the Arizona state capital.