The United States first became a sovereign nation when individual states of the Confederation ceded to the states collectively their several interests in the lands west of the Appalachians which lay east of the Mississippi, north of Spanish Florida, and south of the Great Lakes. This area had been relinquished by Great Britain by the Treaty of 1783 and, with the exception of Kentucky, now became the property of the United States. It was the first area over which the states as a group had complete sovereignty, subject only to the claims of the various Indian tribes. Colonies fresh from success in a fight for freedom from colonialism thus soon found themselves a colonial power faced with the task of governing their own colonies.
William W. Blume & Elizabeth G. Brown,
Territorial Courts and Law: Unifying Factors in the Development of American Legal Institutions-Pt.1-Establishment of A Standardized Judicial System,
Mich. L. Rev.
Available at: https://repository.law.umich.edu/mlr/vol61/iss1/3