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).
Walter
Walter has been climbing back after years of decline. All-time it's been given to 634,804 U.S. babies, the 547th most common name by sound today, peaking at 13,418 in 1918, with 1,381 in 2025.
Walter has no common alternate spellings by sound.
Rising
Source: U.S. Social Security Administration, “National data” baby-names files (1880–2025).