April 25, 1812: The U.S. Congress establishes the General Land Office, which eventually oversees the Homestead Act and other laws enabling the white settlement of the western U.S. In 1946, the agency is rolled into the Bureau of Land Management (BLM), which manages all federally owned land that is not part of a military installation, national Park, national forest, wildlife refuge, or other special-use area.
April 25, 1986: An explosion at the Chernobyl nuclear power plant (at right, with a monument constructed in 2006) north of Kiev in the Ukraine partially melts a reactor core and high radiation levels are reported more than 1,000 miles away in Scandinavia. The Soviet Union relocates 350,000 people, and an estimated 5 million people are affected by the radiation.
Photo: Efrem Lukatsky/AP