The Mississippi Territory is organized from disputed territory claimed by both the United States and the Spanish Empire. It is expanded in 1804 and again in 1812.

The Territory of Mississippi was an organized incorporated territory of the United States that was created under an organic act passed by the Congress of the United States. It was approved and signed into law by President John Adams on April 7, 1798.

The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 states and a federal capital district, Washington, D.C. The 48 contiguous states border Canada to the north and Mexico to the south, with the semi-exclave of Alaska in the northwest and the archipelago of Hawaii in the Pacific Ocean. The United States also asserts sovereignty over five major island territories and various uninhabited islands in Oceania and the Caribbean. It is a megadiverse country, with the world's third-largest land area and third-largest population, exceeding 340 million.

The Spanish Empire, sometimes referred to as the Hispanic Monarchy or the Catholic Monarchy, was a colonial empire that existed between 1492 and 1976. In conjunction with the Portuguese Empire, it ushered in the European Age of Discovery. It achieved a global scale, controlling vast portions of the Americas, Africa, various islands in Asia and Oceania, as well as territory in other parts of Europe. It was one of the most powerful empires of the early modern period, becoming known as "the empire on which the sun never sets". At its greatest extent in the late 1700s and early 1800s, the Spanish Empire covered 13.7 million square kilometres, making it one of the largest empires in history.