Thirteen Clocks is an off-shoot of Parkinson's other book The Common Cause: Creating Race and Nation in the American Revolution. He's just focusing on how race was weaponized to unite the colonies and help hammer home in the colonists' minds that the British were treacherous enemies. Parkinson is exploring the contingent story of how that sense of exclusion (of Black and Native people) occurred at the birth of the USA. The main theme of the book is contingency. Parkinson says that focusing on the opening paragraphs of the declaration of independence leaves readers with an incomplete picture of its meaning. He also stresses that the beginning of the USA and the revolution is very complex for one historian alone to fully grasp.

Through reading Thirteen Clocks it's clear to see the propaganda and stories created guided policy during the Revolutionary war. The stories did not go away after 1776. Proxy stories foreclosed the alternatives after the war was over and these stories mattered because the republic was based on citizenship. Many historians underestimate how Black and Indigenous people were on the minds of the Founding Fathers right at independence. The Founding Fathers weaponized the idea of race, and created a nation where people who were free and white deserved to be the only citizens.