The 1996 US Congress mandated the building of a 14-mile fence at the US-Mexico border, as part of the Illegal Immigration Reform and Immigrant Responsibility Act. By 2004 only nine miles of the fence had been constructed. In 2006 Congress passed the Secure Fence Act legislation requiring the Secretary of Homeland Security to construct a 700-mile fence, in areas of the Southwest border that were deemed the most effective to keep illegal immigrants out of the US. According to the April 2015 Congressional Research Service Report 687 miles of fencing have been constructed along the US-Mexico border. 352 miles primary fencing, 36 miles of secondary fencing, and 299 miles of vehicle barrier fencing. To date, no further fencing has been constructed.