Cassidy is a moderately popular girls' name in United States, ranking #289 in 2016 with 1,123 recorded births. The name reached its all-time peak in 1999 with 3,395 births ranking #99. Since 1996, the popularity has decreased by 60.5%. In 2016, approximately 1 in every 1,577 girls born was named Cassidy. STABLE Recent data shows the name is currently stable.