On this date in 1867, the then territory of Alaska was transferred to the United States from the Russian Empire.
The Alaska Territorial Legislature made it a state holiday in 1917.
The official celebration in the state takes place in Sitka, which was the capital of the territory during Russian occupation. Sitka was the location of the official transfer, and Fort Sitka was the site of the flag lowering and raising ceremony.
There is an 11 hour time difference between Sitka, Alaska and St Petersburg, Russia.