Thanks in part to his rhetorical prowess, President Barack Obama has been credited with restoring prestige to the presidency—in contrast to his predecessor, George W. Bush, who was often derided for sounding vacuous.

But is this observation true, or just an assumption? And how have presidential speeches changed throughout U.S. history? Vocativ wanted to find out.

Using the Flesch-Kincaid readability test—the most well-known reading comprehension algorithm—Vocativ analyzed over 600 presidential speeches, going back to George Washington. We measured syllables along with word and sentence counts, and gave each speech a numerical grade. For instance, a grade of four means the content is accessible to a fourth-grader, while a grade of 12 corresponds to that of a high school graduate, a 15 to that of a college graduate and a 21 or higher to that of a PhD. Ultimately, we drew five conclusions, each of which was analyzed by Jeff Shesol, a historian and former speechwriter for Bill Clinton.

Reading Level of Presidential Speeches

Speeches have grown less sophisticated over time.

“It's tempting to read this as a dumbing down of the bully pulpit,” Shesol explains. “But it’s actually a sign of democratization. In the early Republic, presidents could assume that they were speaking to audiences made up mostly of men like themselves: educated, civic-minded landowners. These, of course, were the only Americans with the right to vote. But over time, the franchise expanded and presidential appeals had to reach a broader audience.”

Speech Length

Over the years, speeches have gotten longer (the larger the circle, the longer the speech).

“One would assume that our decreasing attention span has led to shorter and shorter speeches. I believe that no one, not even a president, ought to give a speech that's longer than 20 minutes. President Clinton used to get tremendous grief from commentators about the length of his State of the Union addresses. But our polling showed that the public liked the long speeches—and people actually stayed tuned. But very few speakers are as compelling as Bill Clinton.”

Speeches to Native Americans

In addresses to Native Americans, the grade level of speeches by Thomas Jefferson and George Washington drops significantly.

“If Washington and Jefferson simplified their language when speaking to Native Americans, they must have seen some kind of gap, either in language or in shared cultural understanding (or both), between themselves and their audience. Presidents today certainly modify their language when speaking to different groups—when speaking in Little Rock, Arkansas, President Clinton would often roll out Southern expressions that you'd never hear him use in a speech at the Council on Foreign Relations. But when a live microphone or camera is in front of them, presidents are really speaking to everyone at once. So I don't imagine you'd see this degree of variation today.”

Grading Lincoln's Speeches

The speeches of Abraham Lincoln ranged in grade from seven to 21. The Gettysburg Address (highlighted in black), one of his shortest speeches, earns a grade of 11.

“This makes clear that length and grade level aren't especially useful gauges for the intelligence (or impact) of a speech. The Gettysburg Address might be short, and the number of syllables in Lincoln's words few, but entire books have been written about that speech. John F. Kennedy and his speechwriter, looking to Lincoln for inspiration, concluded that you should never use a three-syllable word when a two- or one-syllable word will do. That economy of prose characterizes a lot of JFK's speeches.”

Obama vs. Bush

Despite President George W. Bush's reputation as a poor speaker, Obama's speeches are only slightly more sophisticated.

“I don't see a huge discrepancy here. I think President Obama, no more or less than President Bush, tries to pack a lot of nuance and subtext into language that is as plain and straightforward as possible. While President Bush was often inarticulate off the cuff, Bush's speeches were underestimated. There was a crisp formality to a lot of his best speeches, particularly the ones he delivered shortly after Sept. 11.”