Celebrate the Century® 1900s

The USPS launched the Celebrate the Century series in 1998 to mark the end of the 20th century and herald the arrival of the 21st. The series includes 10 sheets of 15 stamps (150 in total), with each honoring important moments from a different decade (1900s, '10s, '20s, '30s, '40s, '50s, '60s, '70s, '80s, and '90s). At the time of completion, it was the longest and most ambitious commemorative stamp series in US history.