Final answer:
The state constitutions were similar because the colonists believed in the consent of the governed and wanted to secure their liberties from abuse by the state.
Step-by-step explanation:
The state constitutions were very similar for two main reasons. First, the colonists agreed that the consent of the governed was the only true source of political authority. This meant that the people should have a say in how their government was run. Second, the colonists wanted to secure their liberties from abuse by the state, so most states implemented mixed governments composed of a legislature, a chief executive, and a judiciary.