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.
The southern United States had the highest percentage of slaves. I am not sure what time period you are talking about but I assume you mean in the United States.
The principle of checks and balances refers to the system, in the American federal system, wherein each branch of government has responsibilities and obligations as it relates to the other branches of government.
The President, for one, is able to veto legislation from the Legislative Branch but a balance on that check is that the Legislative branch may override the Executive branch's veto.
The U.S is about the same size as the Sahara Desert. So Double that is would still be pretty small compared to the rest of the world/.
