First written in the 1970's this still stands up today. Although at the time everyone believed the nasa line/lie that the shuttle system would be flying 50-60 times a year. I am confident that something like the High Frontier O'Neill talks about will come to pass around 2045-50. Whether it will be america that builds them is open to question however e.g. massive delays and dithering regarding the ISS station and what to do next. They seem to be locked into a' plan it then cancel it' cycle.