1904: Child labor is common in both the United States and Great Britain but is a source of controversy. Legislation is proposed to regulate it, including laws that would require children to spend a certain amount of time in school.

Today: Child labor in American and England is highly restricted. Still, several American companies, including Nike, employ factories in developing countries to manufacture their goods at an extremely low cost. These factories often use child labor in sweatshop-like conditions.

1904: People flying in airplanes is an almost unheard-of concept. The Wright brothers made their first successful flight in 1903.

Today: Commercial air travel is common all over the world. Thousands of flights span the globe daily.

1904: Women comprise nearly one-third of the workforce in the United States. They are confined to certain jobs, mostly of a domestic nature, and receive low pay.

Today: Women comprise approximately half...