Let's not get too excited about it.
You've got to understand that the development and the strength of the economy HAS changed since the 19th century. I don't understand the whole concept of looking at historical (long, long term) trendlines - I just don't the logic behind that.
We are in a different economy and should the Dow ever trade above that top trend line, don't assume that it's overbought. I wouldn't be looking at a trendline period any longer than 20 years. 20 years is as far as I would go.
That chart is totally unreasonable, illogical, and very extreme in nature.
For that chart to be true, it would take an event that knocks the country economically back in time. (Major nuclear war on America, unforeseen depression (worst than 1930s), or some other catastrophic event.) And a few more terrorist attacks or a war ARE NOT catastrophic.
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