The State of the Union address has come to be a major moment in the political year. Despite the increased prominence of the speech, the effect of State of the Union addresses on presidential approval has generally been small to non-existent. The average change from before to after the SotU since 1946 has been -0.3 percentage points. Of the 50 post-war speeches for which we have good data, 30 changed approval of the president by 2 percentage points or less. So it is unlikely that President Bush's address Tuesday night will do much to alter public perceptions in either direction, despite the hype around the speech.
The figure above plots change in approval in Gallup poll readings of presidential approval from before to after the SotU. Ideally we'd have polls taken just before and again just after the address. In recent years that has been fairly common, but in earlier years polling was far less frequent. I've measured the days between the speech and the pre-poll and the post-poll. The figure plots the effects for polls taken within 30 days of the address, within 45 days and within 60 days. Where no poll was available within 60 days I've excluded the speech. Even so, some of these polls are far enough apart that attributing effects to the speech per se is suspect. But given the low levels of change, it seems safe to bet that the overall impression of low effects of the speech would not change with a tighter window of polls around the speech.
President Clinton is the one post-war president who enjoyed the greatest success with the SotU. Five of his eight addresses were accompanied by at least a bit of a positive bounce, though even in his case most of these are short of statistical significance.
Perhaps the most surprising result is that Ronald Reagan, the "great communicator" who introduced the practice of having special guests in attendance to recognize during the speech,
did not benefit from his addresses. Only two of his eight addresses showed any positive bounce.
President Bush has likewise not benefited from most of his addresses. Only in 2005 did he get a positive upturn in approval. His other addresses have produced little change in either direction.
So we should dial down any expectations that the State of the Union address is a moment to "salvage a presidency" or "set a new course" or "right the ship of state". The record is clear that those expectations are loftier than the speech has been able to attain.
Cross-posted at Political Arithmetik.