Which system of government shares power between the central and regional governments?

Federalism

Federalism is the system of government in which power is divided between a central government and regional governments; in the United States, both the national government and the state governments possess a large measure of sovereignty.

Federalism is the system of government in which sovereignty is constitutionally divided between a central governing authority and constituent political units. It is based upon democratic rules and institutions in which the power to govern is shared between national and state governments, creating a federation

nafta and the union are used as a trade between other countries these   organizations are used as spokes person for the country