An oligarchy is a system of government where a small number of individuals government a political entity. These individuals can be elected, but normally they are unelected officials who have been given the rights to lead through authoritarian methods.
Democracies are a system of government whereby systems are put into place to allow individuals to vote for representatives or to vote directly on issues related to their political governance.
Republics are democracies in that they involve elections and representation, however, republics institute certain protections for individual rights and liberties usually in a constitution or founding document to prevent the majority from controlling political decisions.
Many women acted as nurses for the wounded in WWI front lines. Most were not allowed to combat, but they could fill roles in other occupations such as the U.S. Army's Signal Corps. and as marine and naval yeomen.
The United States experienced major waves of immigration during the
colonial era, the first part of the 19th century and from the 1880s to
1920. Many immigrants came to America seeking greater economic
opportunity, while some, such as the Pilgrims in the early 1600s,
arrived in search of religious freedom. From the 17th to 19th centuries,
hundreds of thousands of African slaves came to America against their
will. The first significant federal legislation restricting immigration
was the 1882 Chinese Exclusion Act. Individual states regulated
immigration prior to the 1892 opening of Ellis Island, the country’s
first federal immigration station. New laws in 1965 ended the quota
system that favored European immigrants, and today, the majority of the
country’s immigrants hail from Asia and Latin America.