Where is the frontier in America?

Could you elaborate on the concept of "the frontier" in the context of America, and how it relates to the present day? Are we referring to the traditional western expansion, or are there new frontiers emerging in industries such as technology, finance, or even cryptocurrency? How are these modern frontiers shaping the country and its economic landscape? Are there any particular regions or sectors that are leading the way in these new frontiers? And what challenges or opportunities do they present for investors and innovators alike?