With the American mind set on isolationism, the government enacted laws to restrict foreigners from entering the country. The first of these laws was the Emergency Quota Act of 1921, which limited immigration for foreigners to 3% of each nationality living in the United States in 1910. Three years later, this quota was reduced to 2%, and the national origins base was shifted to favor Northern Europeans. Even more extreme, the Japanese, Canadians, and Latin Americans were flatly denied admission. Apparently, immigration was reduced to a mere trickle because Americans wanted as little foreign influence as possible.
To carry out its policy of isolationism, the United States detached itself from international "entanglements". They refused to join the League of Nations, and even struck down the Treaty of Versailles. By hiking up the tariffs, the U.S. also kept European products from entering the American market. Unfortunately, this crippled farmers and manufacturers economically. The lack of outlets for the growing quantity of American products to flow into paved the way towards depression.
The United States seemed determined to keep peace at any cost. Because the Nye Committee placed the blame of World War I on money making munitions such as arms manufacturers and bankers, Washington passed a series of Neutrality Acts forbidding the sale of arms and loans to countries involved in war.