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).
Curtis
Curtis is now well below its former popularity. All-time it's been given to 286,113 U.S. babies, the 1,417th most common name by sound today, peaking at 5,929 in 1962, with 279 in 2025.
By sound, Curtis also includes the spellings Kurtis, Curtiss.
Rising
Source: U.S. Social Security Administration, “National data” baby-names files (1880–2025).