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).
Marcus
Marcus is now well below its former popularity. All-time it's been given to 257,946 U.S. babies, the 482nd most common name by sound today, peaking at 6,261 in 1984, with 1,485 in 2025.
By sound, Marcus also includes the spellings Markus.
Rising
Source: U.S. Social Security Administration, “National data” baby-names files (1880–2025).