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).
Harper
Harper has been easing down from its peak but is still widely used. All-time it's been given to 145,832 U.S. babies, the 57th most common name by sound today, peaking at 11,102 in 2016, with 6,869 in 2025.
Harper has no common alternate spellings by sound.
Rising