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).
Bianca
Bianca is now well below its former popularity. All-time it's been given to 77,759 U.S. babies, the 878th most common name by sound today, peaking at 3,857 in 1991, with 594 in 2025.
Bianca has no common alternate spellings by sound.
Rising
Source: U.S. Social Security Administration, “National data” baby-names files (1880–2025).