The Guardian looks across the pond and finds the Colonies' State of the Union addresses getting "dumber":
Those bubbles show the relative word counts of each State of the Union address (which before FDR was called the President's Annual Message to Congress). We see notably larger word counts for most of the 1800s and early 1900s, largely because Presidents from Jefferson through Taft submitted written reports instead of marching up Pennsylvania Avenue to give Congress what-for in person. Compare the big 20th-century outlier, Jimmy Carter's last State of the Union address, a written report of 33,287 words, the longest such Presidential message.
The Guardian writers derive their "dumber" accusation from the other key data represented in this graph, the Flesch-Kincaid Grade Level of each State of the Union address. The last two centuries show a distinct downward trend in grade level, from James Madison's 21.6 (which suggests even a post-doc would struggle to have grasped what this Founding Father was getting at) to Barack Obama's current average of 9.2 (which means all of my high school students should be able to follow along). Only George Bush the Elder scores lower, at 8.6. George W. Bush, whose intellect we often assail, beat his dad, Obama, Clinton, and LBJ with a 10.0.
This quantitative analysis of one set of specific and arguably useless Presidential messages does not suggest that either our Presidents or the electorate are getting dumber. The fact that Kristi Noem's entries in the Congressional Record have a higher Flesch-Kincaid grade level than Al Franken's proves that Flesch-Kincaid does not measure intellectual capacity. Flesch-Kincaid measures syllables per word and words per sentence. A two-century trend of shorter words and sentences may represent a more inclusive, democratic mindset, with Presidents increasingly aiming their words not just at Washington elites but at the general public.
Flesch-Kincaid grade level for this blog post: 9.53. That puts me between Obama's 9.2 and Bill Clinton's 9.8... still among the top five easiest-reading Presidents.