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).
Lewis
Lewis has been climbing in recent years. All-time it's been given to 156,636 U.S. babies, the 869th most common name by sound today, peaking at 2,731 in 1921, with 736 in 2025.
Lewis has no common alternate spellings by sound.
Rising
Source: U.S. Social Security Administration, “National data” baby-names files (1880–2025).