Wei wrote:

The information I found indicates that on February 9th, 1966, DJIA closed at 995.15 points and never broke the psychological barrier of 1,000 points until November 14th, 1972, when it finally surpassed 1,000 points.

You are correct. I should have checked myself. I got this information from Norm Winski a well known American Financial astrologer who has been astrologically working with stock markets for decades. However, he was 99.5% correct! Following the DJIA nadir of 1942, February 1966 represented the peak of a bull trending market. It would fall after that and not surpass its early 1966 level until 14th November 1972. That was the thrust of the point I was making.
Having said that there can be short crashes which reverse the trend for a while. For example in 1962-1963 there was the so called ‘’Kennedy Slide’’ or ‘’Flash Crash’’ of 1962.

Wei wrote:

What major events occurred in the United States in 1966? I haven't found any particularly significant events.

I also think you may misunderstood the astrology of what I was stating. I simply noted that the market peaked at the time of the final Saturn-Uranus/Pluto opposition in February 1966. It was the astrological cycle I was emphasizing not a particular year. I never claimed 1966 was especially notable. I was simply noting that the Saturn-Uranus/Pluto opposition cycle perfected for the final time on this last perfection. However, that cycle can be traced well before that and I would suggest the opposition first started signs of being activated in 1965. We also have the Uranus-Pluto conjunction all during this period.

General themes of the cycle. US military escalation in Vietnam (and the Dominican Republic). Civil unrest against the government relating to opposition to the Vietnam war and agitation for greater civil rights for African-Americans. We also see two iconic pieces of civil rights legislation and social reform passed in this period. Firstly, the Social Security Act of 1965 which established into law, Medicare and Medicaid. Secondly, The Voting Rights Act of 1965 which was a landmark piece of federal legislation in the United States that prohibits racial discrimination in voting The cycle also saw the assassination of Malcolm X and the Watts riots in Los Angeles. Also numerous spree shooting episodes.

Thank you, Mark, for such a detailed and helpful response. Delving deeply into a subject requires a great deal of energy and time.