Basically the ninth amendment says that if something isn't explicitly outlined as illegal, it's allowed, even if it isn't outlined as a right either. For example, there is nowhere in the law where it says you're allowed to tie your shoes, but because it isn't outlawed, the ninth amendment gives you that right.
The Adams-Onis treaty was the treaty that allowed United States and Spain to divide the remainder of North America in 1819. It is also known by the name of Transcontinental Treaty.
