How to read the band →
Solid line = floor (spellings that unambiguously belong to the group). Shaded band up to the dashed edge = ceiling (the most it could reach if every ambiguous spelling counted here).
Sierra
Sierra is now well below its former popularity. All-time it's been given to 131,877 U.S. babies, the 961st most common name by sound today, peaking at 7,708 in 1998, with 539 in 2025.
By sound, Sierra also includes the spellings Cierra, Ciarra. Spellings sometimes heard the same way: Ciara.
Rising
Source: U.S. Social Security Administration, “National data” baby-names files (1880–2025).