Hypersonic inlet systems and methods are disclosed. In one embodiment, an inlet for an airbreathing propulsion system includes an inboard surface at least partially shaped to conform to a plurality of streamline-traces of a design flowfield approaching an aperture, an outboard surface spaced apart from the inboard surface, an upper surface extending between the inboard and outboard surfaces, and a lower surface extending between the inboard and outboard surfaces, wherein leading edges of the inboard, outboard, upper, and lower surfaces cooperatively define the aperture.