Duncan is a distinctive boys' name in United States, ranking #567 in 2004 with 402 recorded births. This places Duncan in the top 4% of ranked US boys' names for the year. Its actual usage is classified as Uncommon. The name reached its all-time peak in 1997 with 644 births ranking #378. Since 1996, the popularity has decreased by 20.4%. In 2004, approximately 1 in every 4,937 boys born was named Duncan. FALLING Recent data shows the name is currently falling.