But the data-sifting effort didn’t disappear. The National Security Agency, once confined to foreign surveillance, has been building essentially the same system.

The central role the NSA has come to occupy in domestic intelligence gathering has never been publicly disclosed. But an inquiry reveals that its efforts have evolved to reach more broadly into data about people’s communications, travel and finances in the U.S. than the domestic surveillance programs brought to light since the 2001 terrorist attacks.”