I haven’t studied frontier theory, unless you think it’s a way of recouping Frederick Jackson Turner’s concepts, and I’m not familiar with Hollinger, but Greg Grandin’s thesis in The End of the Myth is something like…America is a unique country because it used the eternal frontier as a release valve for social problems, and its wars, until basically the present moment, were all colonial frontier wars.
He wrote an essay at Boston Review that is kind of an adaptation of some of The End of the Myth:
As the United States expanded, first into the West and then into the world, frontier theorists such as Turner—faced with Jim Crow, anti-miscegenation and nativist exclusion laws, the resurgent KKK, Mexican workers being lynched in Texas, the military still massacring Native Americans, and deadly counterinsurgencies in the Caribbean and Pacific—promised that the racism and brutality of outward expansion would soon be relegated to the margins of the nation. Nearly all of these theorists, especially [Frederick Jackson] Turner, were Americanized Hegelians, arguing that history moved forward dialectically. That is, they believed that the unilateral will to power that drove the United States to establish continental dominance would help create a world of universal law, which, if allowed to mature, would then establish dominance over Washington’s will to power.
…And, as one president after another has learned, the easiest way to control the sphere of domestic extremism is to extend the sphere of outward expansion, to channel the passions beyond the frontier. So [Teddy] Roosevelt pushed forward.