The Bloomberg Radio Logs Relating to 9/11 consists of 20 radio logs spanning from midnight on September 11, nine hours before the attacks, through the end of the day on September 17. Each of the tapes covers a four- or eight-hour block of time, e.g. 8am to 4pm.

These tapes were created as part of Bloomberg’s regular policy of recording, or logging, everything that went out over the air. According to Mathisen, this was done in case there were questions about the accuracy of a particular story, or about a commercial had aired as scheduled. Although the tapes are VHS format there is no video; only the audio of Bloomberg Radio was fed to the recorder. VHS tapes were used because, due to their slow speed, they could hold up to 12 hours of audio. Bloomberg's usual procedure was to retain the tapes for a week and then re-use them, but at the end of the week in question Mathisen asked the head of Bloomberg radio if he could have these, and permission was given.

When the Twin Towers fell access to the lower Manhattan financial district became difficult. Subway stations were destroyed, the air was filled with toxic dust, water, electricity and telecommunication systems were damaged or destroyed. Here is an example of the kinds of stories I was reporting regarding access to the affected area:

7:10AM, Thursday, September 13, 2001 Fires continue to burn in the rubble of the World Trade Center complex. The plume of smoke blankets much of lower Manhattan below Canal Street. The New York Stock Exchange Chairman Dick Grasso says the markets will open as early as tomorrow and no later than Monday. Well, let's consider for a minute the hurdles that need to be overcome before the markets can resume operations. First, how to get the 10s of 1,000s of workers to their offices and the trading floor. Much of the financial district remains coated in dust, dirt and debris. Some of this stuff is potentially hazardous. A very large percentage of the employees commute on the PATH train from New Jersey. The PATH train station, located in the bowels of the World Trade Center has been destroyed, and it's unlikely to reopen for years. Car access, forget about it. The Holland Tunnel from New Jersey and the Brooklyn Battery Tunnel, obviously from Brooklyn to lower Manhattan, both of them remain closed. Subway service does not exist below Eighth Street in Manhattan. Throughout the morning here on Bloomberg Radio I'll be discussing the issues that need to be overcome before the markets can reopen. (Don Mathisen, email, 17 Feb 2026)

Recordings include coverage of the actual events; political, business, and financial impacts of the terrorist attacks; information about conditions in and access to the area immediately surrounding the disaster; and what was happening to individuals and families. Mathisen was the reporter on the scene, but dozens of Bloomberg reporters from around the nation and world, company CEOs, government officials, residents and news makers of all kinds can be heard on the tapes.