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).
Willie
Willie is now well below its former popularity. All-time it's been given to 600,438 U.S. babies, the 1,789th most common name by sound today, peaking at 11,091 in 1925, with 183 in 2025.
By sound, Willie also includes the spellings Willy.
Rising
Source: U.S. Social Security Administration, “National data” baby-names files (1880–2025).