United States acquired the area labeled number 6 on the map as a result of which of the following treaties?

The area labeled number 6 on the map was acquired by the United States as a result of the Adam Onis Treaty.

Explanation:

The border dispute that was going on between the United States and Spain was settled through the Florida Purchase Treaty in the year 1819. This treaty demarcated the boundaries between the New Spain province and Florida. Spain was anyway trying to cede Florida the United States as it had become a burden to Spain because sending settlers to the region was no more deemed to be affordable by the Spanish government.