Around the same time, the Spanish gained the Louisiana territory through a treaty with the French. The French forts remained in the territory, running along the Mississippi as far north as Michigan. Later, in 1800, Spain sold this land back to France, which then sold it to America a few years later. | Around the same time, the Spanish gained the Louisiana territory through a treaty with the French. The French forts remained in the territory, running along the Mississippi as far north as Michigan. Later, in 1800, Spain sold this land back to France, which then sold it to America a few years later. |