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).
Isaiah
Isaiah is down from its peak but still widely used. All-time it's been given to 299,702 U.S. babies, the 98th most common name by sound today, peaking at 12,072 in 2006, with 5,939 in 2025.
By sound, Isaiah also includes the spellings Isiah, Izaiah, Izayah, Izaya.
Rising
Source: U.S. Social Security Administration, “National data” baby-names files (1880–2025).