The type of DNA would tell you something. If it's not YDNA or mtDNA, that at least rules out a couple lines. Other than that, you just have to research your ancestors. It's obviously a lot more likely to show up in lines with old immigrations, like colonial ancestors. Generally, anyone ethnically "Hispanic" or "Latino" has a very high chance of having NA ancestry too, so if you have any heritage like that, that's pretty likely where it comes from.