1. On December 20, 1917, Alaska became a territory of the United States. Before this, it had been a district of the Department of Alaska since the United States purchased it from Russia in 1867 for $7.2 million.

2. In 1958, on December 20, an earthquake measuring 7.8 on the Richter scale struck southwest Alaska, causing widespread damage and loss of life. The quake occurred in the middle of the night and triggered a tsunami that caused devastation along the coast.

3. On December 20, 1960, the United States launched the world's first communication satellite, Echo 1, from the Vandenberg Air Force Base in California. The satellite was designed to relay phone calls and television signals around the globe, and it was visible from Alaska as it orbited the earth.

4. In December 20, 1996, the Alaska state flag was officially adopted. The flag features eight gold stars arranged in the shape of the Big Dipper and the North Star, a symbol of Alaska's location in the far north.

5. On December 20, 2020, the first doses of the Pfizer-BioNTech COVID-19 vaccine arrived in Alaska, marking a significant moment in the fight against the pandemic. The vaccine was initially distributed to healthcare workers and other high-priority groups, with the aim of eventually reaching the wider population.