The longest in terms of words was Jimmy Carter’s final message, in January 1981. A written document rather than a speech, the report was 33,667 words long.
The longest orally delivered speech (at least since they started tracking these things in 1966) was Bill Clinton’s January 2000 address, which clocked in at 1 hour, 28 minutes and 49 seconds. Incredibly, that speech was only 7,452 words long, not nearly as long as his 1995 talk, in which he jammed 9,190 words into 1 hour, 24 minutes and 58 seconds. That ’95 address, by the way, was the longest in terms of word count, delivered as a speech.
In the republic’s early days, the House and Senate debated the president’s message and sent formal replies back to him. That practice was eventually deemed too time-consuming and stopped. And while George Washington and John Adams gave their messages in the form of speeches, Thomas Jefferson stopped the practice. It wasn’t until Woodrow Wilson in 1913 that the State of the Union speeches restarted. In all, 76 out of 220 such messages have been delivered by the president, in person.
Two presidents–William Henry Harrison and James Garfield–never delivered such a message to Congress. Both died in office before they were able to.
Silent Calvin Coolidge delivered the first State of the Union (though it was called an annual report until 1934 when FDR called it a “State of the Union” speech) that was broadcast over the radio, in 1923. Harry Truman’s 1947 speech was the first broadcast on television. George W. Bush’s 2002 address (“axis of evil”) was the first livecast from the House’s website.
Over the years, several black speakers from other countries have addressed a joint meeting of Congress. Among the notable examples are Nelson Mandela in 1990 and 1994 and Liberian president Ellen Johnson Sirleaf in 2006.
Until the 1960s, these speeches were delivered around midday. It was Lyndon Johnson who first thought to take advantage of a larger prime time audience, in 1966. That in turn prompted Republicans to ask for chance to respond, starting the tradition of opposition party responses. That first was delivered by House Republican Leader Gerry Ford, who would eventually give his own State of the Union speeches.