Idk what that person was referring to, but the hotbeds of American activism, especially worker activism, were in Americas internal periphery for almost all of the 20th century.
Especially labor and equal rights struggles were often in the rural or suburban (this used to mean living near a factory before it meant that joni Mitchell song about the little houses!) near cities as opposed to in the cities themselves.
Heck, it’s trod ground but the government bombed mine workers in ‘21!