On this day in 1867, officials held a ceremony officially transferring the ownership of Alaska from Russia to the United States, and changed the flag in Sitka, the former capital of Russian Alaska.
The changing of the colors and the guard is commemorated in Alaska each Oct. 18, designated "Alaska Day," an official state holiday in 1917 by the third Territorial Legislature. That same year, territorial lawmakers also created Seward's Day, also a state holiday, to mark on each final Monday in March the signing of the purchase treaty.
To explore a huge number of documents related to the purchase of Alaska, visit the Library of Congress's handy Alaska purchase page, here. It includes a host of resources, including full text archives of speeches, congressional records, treaties, news articles and broadsides.
Of particular curiosity to Alaskans might be a November 1877 Harper's New Monthly magazine article about Alaska's first ten years as a U.S. Territory.