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).
Lachlan has been climbing in recent years. All-time it's been given to 11,368 U.S. babies, the 816th most common name by sound today, peaking at 921 in 2025, with 921 in 2025.
By sound, Lachlan also includes the spellings Lochlan.
Source: U.S. Social Security Administration, “National data” baby-names files (1880–2025).