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).
Anderson
Anderson has stayed fairly steady in American naming for generations. All-time it's been given to 35,646 U.S. babies, the 624th most common name by sound today, peaking at 1,294 in 2012, with 1,079 in 2025.
Anderson has no common alternate spellings by sound.
Rising
Source: U.S. Social Security Administration, “National data” baby-names files (1880–2025).