A Climactic Decade.

The 1920s were a decade of culmination in technology and science. Ideas and inventions on which scientists and engineers had been working for years came out of the developmental stage and into people's lives for the first time.

Cars.

Henry Ford opened his assembly line in 1913, but World War I slowed the growth of automobile ownership. During the 1920s the private car become a fixture of everyday American life. As late as 1919 there were 6.8 million passenger cars on the road in a country of about 105 million people. By 1929 there were 23 million cars for about 122 million people.

Airplanes.

Orville and Wilbur Wright made the first successful manned flight in 1903, but little progress was made until World War I (1914-1918) provided the impetus for improved aeronautic technology. In 1920 the airplane was still mainly a county-fair curiosity. By the late 1920s the major U.S. cities were linked...