Dwight D. Eisenhower and John F. Kennedy interrupted prime-time shows to tell Americans from the Oval Office why they had ordered troops to desegregate schools. Bill Clinton broke into programming from behind the presidential desk three times in a month to explain military actions in Haiti and Iraq. Ronald Reagan, the telegenic former actor, set the record for evening addresses from the Oval Office desk: 29 over two terms. …

The current president? It was three years ago this summer that Mr. Obama gave his only two prime-time addresses from the Oval Office — the first on the oil spill in the Gulf of Mexico, the second on ending combat operations in Iraq. …

“I wouldn’t say the Oval Office address is a thing of the past,” said Martha Joynt Kumar, a presidency scholar at Towson University in Maryland. “It’s just going to be reserved for those presidents and those occasions where they feel they have to use it.” …

But in this century, the Internet revolution and advances in television technology have changed presidents, citizens and the broadcasters who traditionally connected the two.