If I ran for president by Catherine Stier. In cartoons, six kids take turns explaining the election process as if they were running for president. They discuss their decision to run, campaigning, primaries and conventions, debating, being interviewed, meeting the public, voting, and being sworn in on Inauguration Day. Also check out Catherine Stier's If I were president , which describes the job of being president.
Vote  (an Eyewitness book) by Philip Steele. This eyewitness book covers elections all around the world - from ancient Greece through modern times.
America votes: how our president is elected  by Linda Granfield. With this book, kids don't have to wait until they're old enough to vote to get caught up in the excitement of presidential elections.
See how they run: campaign dreams, election schemes, and the race to the white house  by Susan Goodman. Using witty anecdotes and clear explanations, the author takes readers from the birth of democracy to the electoral college; from front porch campaigning to hanging chads.
The Electoral college  by Martha Hewson explains this part of the election process in only 64 pages.