• The American Revolutionary War is sparked by the signing of the Declaration of Independence.  The war lasts until 1783, when Britain accepted the loss of their American colonies by virtue of signing the Treaty of Paris.  

  • The United States purchases the Louisiana territories from France.

  • The War of 1812 occurs between the U.S. and Britain, which is due in part to British restrictions on U.S. trade during the Napoleonic Wars.  

  • The U.S. acquires vast amount of Mexican territory, including California and New Mexico, in the wake of the Mexican War.  

  • Eleven southern states secede from the union to form the Confederate States of America and a civil war ensues.  The northern states had an industrial based economy that favored protectionist policies, and were anti-slavery.  The southern states had an agriculturally based economy which was powered by slave labor.  In addition, these states favored free trade policies as the depended on exporting their produce aboard.  The Confederate states are eventually defeated in 1865 and slavery is abolished.  

  • The United States gains Puerto Rico, Guam, the Philippines, and Cuba following the Spanish-American war.  Cuba, however, becomes an independent country rather than a U.S. territory.  

  • The United States completes construction of the Panama Canal.  The canal greatly expedites international maritime trade by linking the Atlantic and Pacific oceans.  

  • The Wall Street stock market crash triggers the Great Depression, leading to massive unemployment.  

  • The US fleet at Pearl Harbor in Hawaii is attacked by Japanese warplanes; the US declares war on Japan and Germany shortly thereafter.   

  • Nazi Germany is defeated in May, ending the war in Europe.  Japan surrenders in August, following the atomic bombings of Hiroshima and Nagasaki.  

  • The U.S. commits $13 billion to reviving post-war European economies under the Marshall Plan.  

  • The U.S., which had been supporting anti-communist South Vietnamese forces since 1955, escalates its military involvement by deploying regular ground forces.  The proxy war against communist forces, namely the Soviet Union, continued until the signing of the Paris Peace Accord in 1973. 

  • Ronald Reagan wins the presidency and implements his plan of supply side economics, dubbed "Reaganomics".  This economic policy leads to several years of economic expansion, but triples the national debt as a cost.  

  • Congress passes the North American Free Trade Agreement (NAFTA).  NAFTA establishes free trade between the United States, Mexico, and Canada.  

  • Coordinated terrorist attacks on the World Trade Center, and other high profile targets, lead the U.S. to declare a "war on terror", which leads to the subsequent invasion of Afghanistan and Iraq.  

  • The United States faces its worst financial crisis since the Great Depression after Lehman Brothers, a major investment bank, collapses.  "The Great Recession" creates a global financial crisis.  

Sources:

BBC News open_in_new
Britannica open_in_new