Final answer:
Federalism is the constitutional power that allows states to have their own laws and policies, leading to economic and political differences across the United States.
Step-by-step explanation:
The constitutional power that contributes to economic and political differences between states, allowing for a degree of freedom and variation, is the concept of federalism. Federalism is the division of power between the national government and the state governments. One example of this is the Tenth Amendment, which reserves to the states all powers not delegated to the federal government nor prohibited to the states by the Constitution. This allows each state to have its own policies and laws that can significantly impact its economy and political culture, contributing to the diverse landscape of the United States. States might choose different tax policies, business incentives, or labor laws, all of which can play a role in shaping both their own economies and their political character.