Judith St. George (2005)
Chronicles the journey of the Declaration of Independence through American history. Since it was signed in 1776, the Declaration has been rolled up, copied, hidden away, and traveled by horseback, sailing vessel, mail truck, railroad car, and military tank. After being front and center of a new nation, it has escaped two British invasions and survived for more than two centuries of both peaceful times and devastating wars.
The Children's Books and Web Sites bibliography lists more kid-friendly literature about the U.S. government.