THE BURNED OVER DISTRICT

It just takes a little longer. And they still need a warrant to get inside the envelope. But they can make use of all that who and where data just by using a mail cover.

In a rare public accounting of its mass surveillance program, the United States Postal Service reported that it approved nearly 50,000 requests last year from law enforcement agencies and its own internal inspection unit to secretly monitor the mail of Americans for use in criminal and national security investigations.

The number of requests, contained in a 2014 audit of the surveillance program by the Postal Service’s inspector general, shows that the surveillance program is more extensive than previously disclosed and that oversight protecting Americans from potential abuses is lax.

The audit, along with interviews and documents obtained by The New York Times under the Freedom of Information Act, offers one of the first detailed looks at the scope of the program, which has played an important role in the nation’s vast surveillance effort since the terrorist attacks of Sept. 11, 2001.

The audit, which was reported on earlier by Politico, found that in many cases the Postal Service approved requests to monitor an individual’s mail without adequately describing the reason or having proper written authorization.

In addition to raising privacy concerns, the audit questioned the efficiency and accuracy of the Postal Service in handling the requests. Many requests were not processed in time, the audit said, and computer errors caused the same tracking number to be assigned to different surveillance requests.

“Insufficient controls could hinder the Postal Inspection Service’s ability to conduct effective investigations, lead to public concerns over privacy of mail and harm the Postal Service’s brand,” the audit concluded.

The audit was posted in May without public announcement on the website of the Postal Service inspector general and got almost no attention.

The surveillance program, officially called mail covers, is more than a century old, but is still considered a powerful investigative tool. At the request of state or federal law enforcement agencies or the Postal Inspection Service, postal workers record names, return addresses and any other information from the outside of letters and packages before they are delivered to a person’s home.

Law enforcement officials say this deceptively old-fashioned method of collecting data provides a wealth of information about the businesses and associates of their targets, and can lead to bank and property records and even accomplices. (Opening the mail requires a warrant.)

Interviews and court records also show that the surveillance program was used by a county attorney and sheriff to investigate a political opponent in Arizona — the county attorney was later disbarred in part because of the investigation — and to monitor privileged communications between lawyers and their clients, a practice not allowed under postal regulations.

Given the misuse and the potential for much more, we can only hope the inefficiency and inaccuracy was from patriotic postal workers doing a little monkey wrenching. It's about the only hope left.