Metallica's 1991 album was the band's first record to reach number one on the Billboard 200.
The album entered the U.S. chart at the top after its August 1991 release. It sold 598,000 copies in its first week and remained at number one for four consecutive weeks. This marked a major commercial turning point for Metallica, whose previous albums had built a large audience without topping the main U.S. album chart.
The achievement is sometimes described as the album “debuting at number one,” which is accurate, but it is different from saying that it was Metallica's first album to top the chart. Both facts apply to the same release. The record also reached number one in several other countries.
The Billboard 200 ranks albums in the United States using sales and later, in the streaming era, equivalent consumption measures. In 1991, the chart primarily reflected physical album purchases, making the album's immediate performance especially significant for a heavy-metal band.