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).
Isla is one of the fastest-rising names in America right now. All-time it's been given to 87,436 U.S. babies, the 88th most common name by sound today, peaking at 6,981 in 2025, with 6,981 in 2025.
By sound, Isla also includes the spellings Ila, Iyla. Spellings sometimes heard the same way: Ayla, Aila.
Source: U.S. Social Security Administration, “National data” baby-names files (1880–2025).