Hi Bobby, nice to meet you :)
Please help me clarify as I try to assist...
On the question, I'm not positive what a "high" Native American line would be, but if you are referring to an ancestor from very far back (such as 10 generations eluded to in your statement) then there are a couple of ways you could seek the answer. One would be a genealogical "paper" trail showing evidence of relations from you to your parents, them to theirs, etc. until connecting to a known Native American profile. Another way would be to take a DNA test and find results that show Native American ancestry. Ideally you would use both together to be most confident in the results.
On the statement about people living in the same area for 10 generations, I think you are saying that means someone is more likely to be Native American? I'm not sure about that being an indicator; maybe for a particular place and time. Many European settlers lived in the same area of the US for more than 10 generations without intermarrying with Native Americans.
I hope we can find an answer for you, I too have questions about my possible Indian ancestry.
Cheers!