The 7.0-magnitude earthquake that hit Haiti on Jan. 12, 2010, killed more than 200,000 people, leveled much of the capital Port-au-Prince and left 1.5 million Haitians homeless.
As Haitians commemorate the sixth anniversary of the disaster, long-standing political instability and delayed presidential elections continue to undermine reconstruction efforts in the poorest nation in the western hemisphere.
"The path to recovery and long-term development is not an easy one," United Nations Secretary-General Ban Ki-moon said in a statement this week.
"Many Haitians continue to face multiple challenges, including displacement, food insecurity and lack of access to clean water and sanitation," he said.
Below are some facts about what has changed six years after the disaster and the key challenges ahead.
* Haiti has struggled to establish democratic rule after decades of dictatorship, military coups and election fraud. A decision last month by Haiti's Provisional Electoral Council to postpone a presidential run-off election between ruling party candidate Jovenel Moïse and former government executive Jude Célestin amid accusations of fraud and irregularities exacerbates slow construction efforts.
* While most of the rubble has been cleared, many government buildings have yet to be rebuilt. Haiti's parliament is still operating in temporary buildings, while the presidential palace and cathedral remain in ruins.
* The sprawling tent cities where hundreds of thousands of Haitians made homeless by the quake were forced to live in have largely disappeared. But 45,000 Haitians still live in tents and make-shift shelters often assembled from bed sheets, tarpaulin, wooden sticks and string, with little or no access to water and sanitation.
* An acute shortage of housing continues to be a key challenge and few new permanent brick homes have been built since the quake.
* The government estimates Haiti needs up to 500,000 new homes to make up for the pre-earthquake housing shortage, those homes destroyed during the disaster, and demand resulting from urban growth in the densely populated capital.
* A new National Emergency Operations Center was built after the quake to coordinate future disaster response and numerous maps have been produced highlighting those communities most at risk from flooding and other disasters, along with a construction code to improve construction and ensure buildings can withstand future tremors. But experts say the 2010 code is not being enforced and thousands of Haitians in the capital continue to live in informal settlements perched on hilltops.
* Even before the quake, land ownership and unclear land tenure was a thorny issue in Haiti, contributing to violence and poverty in a country where land is concentrated in the hands of a few big landowners. An incomplete national land registry system and unclear land tenure contributes to delays in the building of new homes.
* While the government has pledged to make free and universal education a priority, primary school enrollment is still low - at 75 percent. On average, a Haitian aged 25 years or older has less than 5 years of schooling.
* With half of Haiti's adult population illiterate, raising literacy rates remains a key priority. Roughly 75 percent of children at the end of first grade and nearly half of students finishing second grade could not read a single word, according to an assessment by the U.S. Agency for International Development (USAID).
Sources: International Organization for Migration (IOM), U.S. Agency for International Development (USAID) and Center for Economic and Policy Research (CEPR)