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).
Leighton has climbed over the years and is holding near its high. All-time it's been given to 38,122 U.S. babies, the 455th most common name by sound today, peaking at 1,782 in 2019, with 1,653 in 2025.
By sound, Leighton also includes the spellings Layton, Leyton.