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).
Marco
Marco is now well below its former popularity. All-time it's been given to 81,356 U.S. babies, the 695th most common name by sound today, peaking at 2,232 in 2005, with 934 in 2025.
By sound, Marco also includes the spellings Marko.
Rising
Source: U.S. Social Security Administration, “National data” baby-names files (1880–2025).