The transcontinental railroad's construction touched the lives of hundreds of thousands of people. Some desired it, some built it, and some did everything in their power to stop it. Browse a photo gallery of settlers, Native Americans, and workers whose lives were affected by the railroad as it traversed the West.
Originally settled as a mail stop, Las Vegas changed from an Old West vacation town, to a mafia haven, to the "Atomic City" and "Sin City."
A brilliant scientist, Oppenheimer was tasked with the development of the atomic bomb during World War II.
The historic journey of Apollo 8 captivated the world in 1968 -- a bright spot in a year marked by political assassinations, race riots, and the Vietnam War.
While the U.N. debated strategies for control of atomic energy, the U.S. Navy was preparing for nuclear tests on Bikini Island.
The worldwide migration by eager gold-seekers turned California into a land of opportunity and fierce competition.
After 18 years of struggles, the Golden Gate Bridge opened on May 27, 1937.
Native Alaskans, oil company representatives, environmentalists, politicians, and others tell the story of the 800-mile pipeline.
The international race to develop biological weapons during the 20th century.