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).
Donald is now well below its former popularity. All-time it's been given to 1,420,387 U.S. babies, the 1,192nd most common name by sound today, peaking at 30,518 in 1934, with 395 in 2025.
Donald has no common alternate spellings by sound.
Source: U.S. Social Security Administration, “National data” baby-names files (1880–2025).