Begun during the Civil War, the transcontinental railroad employed 20,000 men, mostly immigrants, who built the iron road with their bare hands.
Major Walter Reed's discovery in 1900 that mosquitoes spread yellow fever halted an outbreak and led to the disease's eventual eradication.
In 1960, Francis Gary Powers' U-2 spy plane was shot down over the Soviet Union.
Though first seen only as an expensive luxury, Alexander Graham Bell's telephone soon transformed American life and became a necessity.
"The Wizard of Menlo Park," Inventor Thomas Edison, built the first practical light bulb and revolutionized the world.
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.
George Eastman introduced the Kodak and Brownie camera systems and transformed photography into something anybody could do.
Brothers Wilbur and Orville Wright built a flying machine that made its first flight in Kitty Hawk, North Carolina in 1903.