Uh uh. While our decline started during the Nixon administration, it was not his policies that caused it. The demise of the middle class began with the Lewis Powell memo in 1971. As a result of that American businesses began to pour massive amounts of money into a campaign to redesign the economy to enable corporate control. Think tanks like the Heritage Foundation and the American Enterprise Institute formed at that time, and the COC changed from a local business group into a national lobbying group for big business. Corporations began throwing money around at politicians at unprecedented rates.

These changes started slowly, and began to have a real effect during the Carter administration. Carter was not a fan of unions, he was responsible for a defeat of a major labor bill, and he refused to negotiate in good faith with the air traffic controllers, planning to break the union in the following year, which resulted in PATCO endorsing Reagan.

But it was during the Reagan years that everything came to fruition. You can find many charts like the productivity chart in this article that have similar breaks around 1980, charts of education, health care, mental health, trade, the deficit and debt, and many other issues. 1980 was the year that changed America forever.

An interesting book that lays out the best timeline presentation is Winner Take All Politics, by Jacob Hacker and Paul Pierson, written in 2011, but still very relevant today.