Prez. the first teen President of the US, makes his debut in Prez 1 (Aug/Sept 73), in a story by Joe Simon and Jerry Grandenetti.
In 1971, as the comic informs us, the voting age in the US was lowered to 18 from whatever it had been before that. 21 would be my guess. This series envisions a reality in which young people vote in large numbers, making it clearly a fictional world. Prez Rickard is a young man from an obscure town, Steadfast, who likes to fix clocks and watches.
Government is shown to be wildly corrupt and in the pocket of business interests, so they get that part right. The villain of the story is Boss Smiley, shown with a happy face head, which is probably the most clever element of the strip. The people are beginning to turn against their government, so Boss Smiley realizes they need a candidate they can market well, and a young one, so they can grab that all powerful youth vote. They choose Prez, based on his repairing of clocks, and convince him to run for senator of his state.
As Boss Smiley and company head from Steadfast we briefly get introduced to a native youth, Eagle Free. Smiley tosses his cigar out of the window of his limo, and it is about to start a forest fire until Eagle Free puts it out. Not that Smiley notices or cares.
Prez becomes senator, and has total faith in Smiley. He goes through with plans to build a highway into Steadfast, and helps blow up a dam as part of the construction. This brings him into conflict with Eagle Free. The animals that Eagle Free lives with lose their habitat because of the destruction of the dam. This includes gorillas and elephants, who apparently wander loose in this version of the US.
It's Eagle Free who begins the true education of Prez, and together they break into Boss Smiley's office, where Prez learns how corrupt his mentor truly is. Smiley catches them, and intends to withdraw his support, but it is too close to election time for this to matter. See, with all the young people elected to Congress along with Prez, they lowered the age one can run for president to 18, and Prez is one of the candidates.
So Prez winds up winning, and becomes the first teenage president.
Eagle Free becomes the head of the FBI, which seems kind of random. The story closes by teasing the reader that they will never guess who Prez's vice president will be. And that is true. Because it will be a character who did not appear at all in this issue, so how could anyone possibly guess it?
Boss Smiley is not seen again until Neil Gaiman's revival of Prez in the pages of Sandman.