Cassidy vs Sidney
Cassidy leads today (#541 vs #1,323), though both are past their peak.
145 years, head to head
Babies named Cassidy and Sidney per year in U.S. Social Security records, 1880–2025.
Head to head
2025 rank
#541 (girls)
#1,323 (boys)
Babies named in 2025
558
146
Peak year
1999
1912
Trend
Declining since 1998
Declining since 1994
Usually for
Girls
Girls & boys
Lifetime births
60,848
84,202
Try another matchup
Cassidy against names whose popularity has moved like its own.