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).
Alonzo
Alonzo is now well below its former popularity. All-time it's been given to 46,109 U.S. babies, the 943rd most common name by sound today, peaking at 651 in 2022, with 590 in 2025.
Alonzo has no common alternate spellings by sound.
Rising
Source: U.S. Social Security Administration, “National data” baby-names files (1880–2025).