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).
Frederick
Frederick is now well below its former popularity. All-time it's been given to 354,782 U.S. babies, the 756th most common name by sound today, peaking at 6,691 in 1952, with 879 in 2025.
By sound, Frederick also includes the spellings Fredrick, Frederic, Fredric.
Rising
Source: U.S. Social Security Administration, “National data” baby-names files (1880–2025).