In a June 2, 2010 article on Mariah Carey, Billboard lists the Top 5 Best Selling Female Artists in SoundScan history.
Shania is the 3rd Best Selling Female Artist in SoundScan history.
[Note: SoundScan began tracking actual U.S. album sales in 1991.]
According to the Billboard article, here are the top 5 Best Selling Female Artists in SoundScan history:
1. Mariah Carey -- 52.6 million 2. Celine Dion -- 51 million 3. Shania Twain -- 33.9 million 4. Britney Spears -- 31.5 million 5. Reba McEntire -- 29.3 million