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).
Cooper
Cooper has been climbing in recent years. All-time it's been given to 130,876 U.S. babies, the 87th most common name by sound today, peaking at 7,899 in 2025, with 7,899 in 2025.
By sound, Cooper also includes the spellings Kooper.
Rising
Source: U.S. Social Security Administration, “National data” baby-names files (1880–2025).