Metallica's highest-charting US album before The Black Album topped the Billboard 200 was ...And Justice for All, which reached number six.
Released in 1988, ...And Justice for All was Metallica's fourth studio album and its previous full-length release. Its number-six peak showed that the band had already achieved substantial commercial success, but it had not yet reached the top position on the main US album chart.
The Black Album changed that pattern. It became Metallica's first album to top the Billboard 200, debuting at number one and remaining there for four consecutive weeks. The shift reflected both the band's growing audience and the more streamlined musical and production approach associated with the new record.
The answer is sometimes confused with Master of Puppets, another major Metallica album. That 1986 release reached number 29 in the United States, while Ride the Lightning peaked lower still. Thus, among the band's pre-Black Album studio albums, ...And Justice for All held the strongest US chart position.