A Border Surge amendment added to the Senate immigration bill calls for 700 additional miles of border fencing, along with 70,000 additional U.S. border agents. Constructing the fence "would come with a mammoth and unpredictable price tag," writes Tracy Connor. "The per mile costs to build the fencing varied considerably because of the type of fencing, topography, materials used, land acquisition costs, and labor costs, among other things," according to a report from the Government Accountability Office. U.S. Customs and Border Protection has already spent $2.4 billion to build 670 miles of single-layer border fencing. The amendment is scheduled for a vote tonight.