Dr. Alfred Crosby, author of Epidemic and Peace 1918: America's Forgotten Pandemic.
Major Walter Reed's discovery in 1900 that mosquitoes spread yellow fever halted an outbreak and led to the disease's eventual eradication.
Begun during the Civil War, the transcontinental railroad employed 20,000 men, mostly immigrants, who built the iron road with their bare hands.
The story of the polio crusade pays tribute to a time when Americans banded together to conquer a terrible disease.
In 1934, American polar explorer Richard Byrd became the first to experience winter in Antarctica's interior.
After 18 years of struggles, the Golden Gate Bridge opened on May 27, 1937.
The most daring and innovative accomplishment at the turn of the 20th century.
Equipment failure, human error and bad luck led to the country's worst nuclear accident in 1979.
The effort of pioneering researchers to conceive babies through in vitro fertilization.