Why are 1990 American dollar bills worth more than 1989 American dollar bills?

1990 American dollar bills can be worth more than 1989 bills primarily due to collector interest and rarity. Bills from certain years may have lower production numbers or unique features that make them more sought after by numismatists. Additionally, the condition of the bills can significantly affect their value, with higher-grade notes fetching premium prices. Collectors often pay a premium for bills from specific years, leading to increased value for those from 1990 compared to 1989.