Was American change in governmental structure in 1787 a unitary to confederal change?

No, the American change in governmental structure in 1787 was not a shift from a unitary to a confederal system. Instead, it represented a transition from a loose confederation of states under the Articles of Confederation to a stronger federal system established by the U.S. Constitution. This new framework created a balance of power between the national and state governments, allowing for a more centralized authority while still preserving state sovereignty.