Who had the first million dollar selling recording?

In 1958 The Gold® record award is introduced. The Gold® album is awarded for $1 million in sales based on the manufacturer's wholesale price. The Gold® single signifies one million copies sold. Perry Como's "Catch A Falling Star" (RCA Records) is the first Gold® single officially certified by the RIAA® on March 14.

The RIAA was formed as a trade organization for record labels and they dubbed their awards Gold® records, even eventually registering as service or trademarks the terms "Gold" and later "Platinum®" and "Multi-Platinum™ ". Initially, Gold record awards were bestowed for singles or 45s that had sold 1 million copies and albums/LPs which had sold one million dollars worth ... The first RIAA Gold award was issued on March 14, 1958 for the 45 rpm single "Catch A Falling Star" by artist Perry Como. On July 8, 1958, the first Gold LP was awarded for the cast soundtrack of Oklahoma! sung by Gordon MacRae:

https://musicgoldmine.com/blogs/news/who-was-awarded-the-first-gold-record

The answer to the question appears to be the Oklahoma soundtrack, in July 1958 https://en.wikipedia.org/wiki/Music_recording_sales_certification
Several different thresholds have been in use at different times and places for both album and single awards. Some of these were based on units sold and others on the value of retail sales. The first official designation of a "gold record" by the RIAA was established for singles in 1958, and the RIAA also trademarked the term "gold record" in the United States. On March 14, 1958 the RIAA certified Perry Como's hit single "Catch a Falling Star" as its first-ever gold record, and the Oklahoma! soundtrack was certified as the first gold album four months later