Imperialism is the practice of a policy in which a nation extends its control off their borders on other countries. It is the extension of ruling over foreign nations. It is the process by which one country dominates another directly, by political means, or indirectly, by economic means.
First, economic opportunities grew. The United States saw potential in starting international markets, such as the open door policy for china which enhanced the trade between foreign countries and the US. Or Japan, where they were forced to trade by Matthey Perry. The U.S government also wanted control of some Pacific islands to use as refuelling and repair stations for its naval vessels. Therefore, Seward championed the annexation of the uninhabited Midway Islands in 1867. Also U.S signed a treaty with Hawaii and this agreement allowed Hawaiians to sell sugar in the United States duty-free.
Secondly, cultural superiorty made people think that they should spread their beliefs, and thought that they were better than all other groups of people, which is nationalism. Thirdly, humanitarian goals spurred on imperialists, who believed that second world countries would need their occidental medicine techniques & doctors. Finally, the U.S was getting behind other countries concerning economical, military, politically, etc… power therefore they wanted to be in the same level of Europe and therefore they did so by blaming it on social Darwinism and Manifest Destiny.
Examples of Expansions
There are many examples for why imperialism expanded, when the Secretary of State Seward 
bought Alaska from Russia in 1867 and convinced the Senate that Alaska had many natural resources that was benefiting for them. Seward also annexed the Midway Islands to use as refuelling stations for the navy.
The example of American imperialism that stood out the most was their meddling between the Cubans, who wanted their independence, and the Spanish who were occupying Cuba. Spain refused to let Cuba away, therefore the Spanish-American War started and was ended when the US Navy sank all the Spanish ships. After the Spanish-American War, The Treaty of Paris was passed, and Spanish lost all its colonies in the Atlantic and Pacific Ocean. It had ended Spain's power, yet strengthened the United States since they went form a continental power to an empire by acquiring Philippines & Puerto Rico. However, since the principles of the Constitution of the US states that everyone has a right to liberty & the Cubans didn't want to be ruled by the US, the US was forced to give them their independence. The Platt Amendment was passed to allow the US to intervene in Cuba whenever they pleased, and to settle navy places along the coasts, and it made it fair.
Puerto Rico did not become independent like Cuba, United States maintained it a military government in the territory until 1900. This military aided the development of the infrastructure and education.
Finally, The Annexation of Hawaii was also crucial to the imperialistic expansion of United States. Hawaii became increasingly important to United States business interests. Hawaii also leased Pearl Harbor to the United States as a fueling and repair station for naval vessels. In 1898, Congress approved the annexation of Hawaii. Hawaiian sugar was also sold in America as a duty free.
Pros and cons
A positive effect is seen when the larger nations gave to the smaller colonies. The nations built 
roads, canals, and railways. Showed them the telegraph, newspaper, established schools for them, gave them the blessing of their civilization, and overall made them economized. They were part of modern culture after this occurred. Another positive effect is how the colonial governments introduced improved medical care, and better methods of sanitation. There were new crops; tools and farming methods, which helped, increase food production. These changes meant less death to smaller colonies, and overall improve the state of living. They now could live longer and have better sanitation compared to the earlier imperialism. A negative effect is that the colonies doing the developed countrys hard work did not civilize the smaller colonies. They were put to work as cheap labor. They had no freedom, had to do what the big country said since it has so much power over them, they were exploited and were taken advantage of. The negative effect of imperialism is when many parts of the country is ruled badly by the other country, many local citizens get the foreign disease, many had no money to pay heavy taxes, and many more bad things. Sometimes even the cultures in that particular country was forgotten, lost, and then not known. These negative effect make a big difference on how the world is today and how it must be.
Arguments for and against
The arguments against imperialism were that the small colonies that belonged to United States didn’t have the same Constitution and law to follow which was very disadvantageous for the 
small colonies since they wanted to be part of a developed country to be able to thrive as citizens. Anti-imperialists also believed that imperialism could lead to the break down of the nation’s democratic foundations. Finally, the last drawn reason was that countries were opposing the fact that Americans were feeling haughty about their culture and discriminating other cultures.
There are 3 arguments for imperialism: promoting economic growth, protecting American security & preserving the American spirit. Workers and farmers started convincing firm and political leaders that the US markets must expand abroad for their overproduction led to financial panics and economic depressions. This also lead to business leaders going one step further and investing directly in the economies of other countries. For example Minor C. Keith, who began the idea of the banana republics. Those who favored strong US Navy formed a second force, and strived for the pushing forces of expansion. They wanted to build modern steam powered teel-hulled ships to protect over seas trade. As Mahan said, the US needed a powerful navy to protect those markets from foreign rivals. Thus, the Congress established a Naval Advisory Board, which would manage the navy’s budget. Finally the Naval Act called for the construction of more battleships, gunboats, torpedo boats, and cruisers.
Op/ Ed
Imperialism is never considered as a good or bad. Colonies inside colonies would fight because 
they wanted independence and have their own government and rule. There were many ethnics group that had nationalistic feelings but could not accomplish anything and become a free nation because of Imperialism. The developed countries ran for things they really wanted and they got it. They wanted raw materials, markets for goods, balance of power and they also felt as though they needed to help smaller nations as though it was their destiny. In their point of view they thought they were helping people but really all they were doing was hurting the smaller colonies. Developed countries were destroying ethnic groups and causing civil wars between smaller nations. To conclude, negative effects of imperialism have more impact on people therefore I believe solemnly believe that Imperialism should be abolished.Bibliography:
wikis.nyu.edu/.../imperialism.jpg
southbronxscholars.files.wordpress.com
analepsis.wordpress.com/.../18/empire-contcult/
mwhcp-per6.wikispaces.com/imperialism
4.bp.blogspot.com/.../s400/Imperialism+2.jpg
Progressive people are people who are concerned with the problems emerging from immigration, industrialization and urbanisation. They can focus in such issues such as; catalysing a number of fundamental changes in the American social and political manners, focusing on humanizing the modern city or improving workplace conditions. 
Politically, Progressive Americans wants to change the political system by eradicating corruption and enfranchising women. These progressive Americans are trying to help because they want their country, America, to be faithful and be able to have a civilized country where citizens face problems and where every citizen should be equal and money won’t change decisions of people.
Despite the ambitions of progressive people to improve the living conditions in the American Society, there are enormous obstacles influencing the changes they could envision, including; hostility toward labour unions, indifference regarding the rural poor and racism toward African-Americans and these concerns are still affecting the American Society nowadays.
