From the US Department of State regarding the 1915 action:

Under interventionist policies of the early 20th century, President Woodrow Wilson sent the United States Marines into Haiti to restore order and maintain political and economic stability in the Caribbean after the assassination of the Haitian President in July of 1915. This occupation continued until 1934.

Read more at http://www.state.gov/r/pa/ho/time/wwi/88275.htm

From the National Defense University regarding the 1994 action:

Operation Uphold Democracy was a U.S.-led, multinational military intervention authorized by the UN to restore the legitimate, democratically-elected government of Haiti to power. Democracy was, at best, a weak concept in Haiti, and it had been almost extinguished by a military coup in 1990. The operation provided the security needed to resume the development of democratic government in Haiti. Uphold Democracy removed the military ruler and demobilized the repressive Haitian army, making the return of Haiti’s president and the transition to a new democratically-elected president in 1996 possible. UNMIH oversaw these elections and the formation of the Haitian National Police (HNP).

Read more at http://www.ndu.edu/inss/strforum/SF_78/forum78.html

Even though I was in the fifth grade at the time, I can recall seeing news reports regarding the 1994 intervention. Perhaps this time around the US can finally help and improve the nation of Haiti and its people.