December 11: National Days, Holidays & Observances
December 11 is day 345 of the year, with 20 days left until the year ends. In 2026 it falls on a Friday. There are 2 observances on this date.
International Mountain Day
International Mountain Day is observed on December 11 in order to raise awareness of the value of mountains to human life.
National App Day
The National App Day is celebrated on December 11 every year in America and other surrounding countries. Apps evolved with the advancements…