Despite the billions of dollars spent on border security, it's hard to tell whether the money is accomplishing what it's supposed to, two federal oversight agencies tell Congress, says the Medill News Service. The Government Accountability Office and the Congressional Research Service say that even with the amount of border data collected by the federal government, there's no adequate barometer to measure the effectiveness of the enforcement efforts. Since 2011, the Department of Homeland Security has used the number of apprehensions of illegal entrants on the Southwest border as a measure of success. Before that, the main measure was the number of miles of the southern border that were secured. Marc Rosenblum, who wrote the Congressional Research Service report, said, “We do not know if a decline in apprehensions is a good thing because fewer people are attempting to enter or a bad thing because more of them are succeeding.” The RAND Corp. has worked with DHS to develop a way to measure the effectiveness of border security. The department is expected to come up with a plan to establish goals by the end of the year.