1) Seeking "tax shelters" through investment. Very inefficient, however. 2) Factors other than the tax system. Correlation != causation, IOW. The U.S. had (som

1) Seeking "tax shelters" through investment. Very inefficient, however. 2) Factors other than the tax system. Correlation != causation, IOW. The U.S. had (something approximating) the only standing industrial infrastructure in the world post-WWII. It's also worth noting that the Kennedy tax cuts probably released a lot of pent-up economic energy. Similar tax cuts under different circumstances may not have the same effect - there had been widespread privaiton in the US from 1929 until the '50s, and this sort of acted as a "second stage" booster. 3) A general cultural civic-mindedness. I recently listened to a presentation of Devon Energy's CEO, and his father started a fund in energy and wanted it structred as a registered security , one of the first , and was told "you don't need to do that" by the SEC, but he persisted because he felt that was better. He then contrasted that now with people spending lots of money to avoid SEC regulation. That highlights the level of culture shift since then.