More than 56m people watched the TV broadcast of President Obama's announcement about Osama bin Laden

"On Sunday, May 1, 2011, President Obama announced that U.S. military forces killed Osama bin Laden in a targeted attack. The address was carried live from approximately 11:35 PM- 11:44 PM ET on 9 networks. The sum of the average audience for those networks was 56,512,179 viewers, with a combined household rating of 33.9. The networks carrying the address included ABC, CBS, NBC, TEL, UNI, CNN, FOXNC, HLN and MSNBC."

Source:  Nielsen, 3rd May 2011