Strong American Chess Tournaments

My latest 'On the Cover' post, for August 1966, covered the Second Piatigorsky Cup and quoted Chess Life:-

This double round robin, eighteen games over a one-month period, will undoubtedly rank with the greatest chess competitions of all time.

While that is certainly true, how many other American tournaments can be considered among the 'greatest chess competitions of all time'? I turned to Wikipedia's List of strong chess tournaments to help answer the question. Although the list is inconsistent, it's a start. I extracted the 981 events listed on the page, loaded them into a database, and isolated the American events.

I found 56 American events including 23 venues. Of these, 26 were played in New York. The table on the left shows the 25 most recent events.

Many of these events I don't recognize (1940 Dallas?) and further research would undoubtedly increase my limited knowledge of American chess history. There are as many tournaments listed in the 10 years leading to the 1972 Fischer boom as there are in the 40+ years following it.

The 30 year gap between 1982 Chicago (won by Huebner) and the start of the Sinquefield series is particularly noteworthy. Where were the strongest American players playing during that time?