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).
Ivory has been climbing in recent years. All-time it's been given to 23,114 U.S. babies, the 826th most common name by sound today, peaking at 840 in 2025, with 840 in 2025.
Ivory has no common alternate spellings by sound.
Source: U.S. Social Security Administration, “National data” baby-names files (1880–2025).