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).
Ruth
Ruth has been climbing back after years of decline. All-time it's been given to 838,901 U.S. babies, the 440th most common name by sound today, peaking at 26,156 in 1920, with 1,781 in 2025.
Ruth has no common alternate spellings by sound.
Rising
Source: U.S. Social Security Administration, “National data” baby-names files (1880–2025).