The tallest mountain question can be argued on several fronts. One being that Hawaii, while politically is part of North America, geographically is not. Also "tallest" is ambiguous. Tallest from its base? Highest in elevation? Considering you give the elevation above sea level one would have to assume you're asking for highest in elevation. In that case Denali is much taller than Mauna Kea. And Denali is actually in North America. In that context Mauna Kea wouldn't even rank inside the top 50 tallest mountains.