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).
Lydia
Lydia is down from its peak but still widely used. All-time it's been given to 187,317 U.S. babies, the 278th most common name by sound today, peaking at 3,652 in 2014, with 2,692 in 2025.
Lydia has no common alternate spellings by sound. Spellings sometimes heard the same way: Lidia.
Rising
Source: U.S. Social Security Administration, “National data” baby-names files (1880–2025).