The principal challenges of securing the U.S.-Canadian border involve the coordination of multiple partners. The results of the DHS (Department of Homeland Security) efforts to integrate border security among its components and across federal, state, local, tribal, and Canadian partners are unclear. The Government Accountability Office (GAO) was tasked to address the extent to which DHS has improved current conditions while also reporting on past conditions and the progress made in securing the northern border.
http://www.gao.gov/new.items/d1197.pdf