On 2 November 1971, the Delphos Ring incident occurred in Kansas. Physical trace evidence claims have been made in relation to a grey/white ring on the farm of Mr and Mrs Johnson and their son Ronald Johnson. (Commonly referred to as the “Delphos Ring” incident).

This incident is Case 60 in Isaac Koi's "Top 100" article,  since it was referred to in 49 of the books covered by that article.

The National Enquirer reported on 27 May 1973 that it was awarding the Johnson family $5,000 “for supplying the most scientifically valuable UFO evidence in 1972”, following the recommendations of the members of its “blue ribbon” panel of UFO experts.

This incident has also featured in lists by various UFO researchers of the top UFO cases, including the following:

• a list by James Carrion, the International Director of the Mutual UFO Network, of the “top 10 cases” in an interview in 2006.

a list of cases produced by Stanton Friedman for the Fortean Times in 2007 as part of a survey of various researchers of the ten cases from 1947 onwards that interested them the most.