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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).
Royal
Royal has been climbing in recent years. All-time it's been given to 24,394 U.S. babies, the 670th most common name by sound today, peaking at 1,217 in 2021, with 765 in 2025.
Royal has no common alternate spellings by sound.
Rising
Source: U.S. Social Security Administration, “National data” baby-names files (1880–2025).