President Kennedy scribbled "Vietnam" over and over, drawing a box around the word each time.
President Eisenhower sketched a picture of himself looking larger than life, bare-chested, and with a head full of hair.
President Reagan doodled smiling cowboys alongside love notes to his wife.
Presidents Carter and Ford left no scribblings.
It's not the first thing a scholar might search for in the public record, but presidential doodles hold a certain fascination for the historically minded.
"Doodles are often the last remnants of unconscious, unscripted presidential writing," said David Greenberg, a historian who examined two centuries of scribblings by commanders in chief for a book appropriately called "Presidential Doodles."
The book includes the absentminded scratchings of 24 presidents -- plus a note from President Bush -- collected from public records and archives across the country.
Greenberg cautions against reading too much into a doodle, but he believes they offer a glimpse into the president's private side.
"So much of what we hear from a president is planned and vetted by focus groups. It's un-spontaneous. You see in these doodles the exact opposite. These doodles are done not only without regard to what the public is going to think but also what the president himself is thinking. It's often unconscious."
The doodles do seem telling.
Take Kennedy, for example.
There's the boxed-in rendering of "Vietnam," which has an obsessive anxious feel to it.
On a memo produced during a visit by the Shah of Iran, Kennedy doodled the words "Iraq," "Syria" and "Egypt," and put boxes around each word as well.
Greenberg views these sketches as a window into Kennedy's problem-solving process.
"He's drawing these doodles in meetings during times of high international tension. And the doodles show him trying to contain problems like Vietnam and the Middle East," Greenberg said.
"You see this contained energy. You feel him working within the constraints of the time and the Cold War."
In another Kennedy doodle with seeming modern-day relevance, he wrote "9/11" repeatedly and the word "conspiracy" next to it.
He also inverted the numbers, writing "11/9."
It turns out that was the tally of a committee vote, not a foreshadowing of the Sept. 11, 2001, attacks.
Eisenhower's doodles also seem to be a window into something -- if not his mental process then maybe his ego?
He was a frequent scribbler, and his renderings are well executed.
In fact, America's 34th president was a practiced landscape painter.
In his doodles, though, he seems a fan of the self-portrait.
On one memo with the heading "Cabinet Paper -- Privileged," he covers a third of the page -- including text about the executive branch's transportation responsibilities -- with a massive pencil sketch of his head, with hair.
Another memo outlining the agenda for "The Legislative Leadership Conference, Monday June 28, 1954" is scribbled over with a gunboat and a rendering of himself with huge muscles, a bare chest, thick hair, and a much younger face.
Greenberg says that picture "shows him as this Charles Atlas style figure … with a kind of virility. It was during a time when America was exerting its military force abroad, and Eisenhower is drawing a kind of correlative to that."
Most of Eisenhower's drawings incorporate weaponry -- knives, boats and missiles -- perhaps not surprising from a general.