This is one of the collections of 63,700,494 records on the FamilySearch.org website that has only been available for a relatively short time. Here is the description of the files from the FamilySearch.org entry shown above.

The Social Security Administration created these records to track the earnings of US workers and determine benefit entitlements. The publishable index only contains information for deceased individuals and was gathered from all three record types in the collection: applications, deaths, and claims. Each compiled record includes fields for the name of the deceased, social security number, parents’ names, gender, birth city and state or country, birth date, and death date.

Here is an example of the content of a record for one of my relatives.

Several of my searches for other relatives did not find any records and I am guessing that they either died too recently or did not have a social security account. You can see from this record that Donnette did not apply for Social Security coverage until she was about 73 years old.There is a more detailed description of the record set in the FamilySearch Research Wiki.

https://www.familysearch.org/en/wiki/United_States,_Social_Security_Numerical_Identification_Files_(NUMIDENT)_-_FamilySearch_Historical_Records

I will be highlighting other useful collections from time to time.