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).
River
River has been climbing in recent years. All-time it's been given to 59,351 U.S. babies, the 141st most common name by sound today, peaking at 5,430 in 2022, with 4,540 in 2025.
River has no common alternate spellings by sound.
Rising
Source: U.S. Social Security Administration, “National data” baby-names files (1880–2025).