The visit is intended to underscore US commitment to rebuilding Haiti
The First Lady of the United States, Michelle Obama, has made an unannounced visit to Haiti.
It was her first official trip overseas without US President Barack Obama since he took office last year.
She spent several hours in the Haitian capital Port-au-Prince, visiting projects set up in the wake of the devastating earthquake in January.
Mrs Obama then flew on to Mexico for a previously announced visit due to last three days.
AT THE SCENE
Laura Trevelyan, BBC News Haiti
Mrs Obama flew over Port au Prince by helicopter, and was greeted by the Haitian president and his wife by the ruins of the presidential palace.
She described the destruction she witnessed as "powerful".
Next stop was a school where the First Lady clapped along as the children sang and danced to greet her. "Let's hold hands like good friends," they sang.
In one of the buses serving as a classroom, Mrs Obama sat at a small table and painted colourful pictures with the children.
Mrs Obama then toured a partly ruined college. One woman looking on told me she hoped the visit would focus attention on the plight of Haitians.
As the US winds down its military presence, Mrs Obama's visit is meant to underscore the United States long-term commitment to helping the people of Haiti.
The trip was kept a secret for security reasons.
The White House said the aim of the visit was to "underscore to the Haitian people and the Haitian government the enduring US commitment to help Haiti recover and rebuild".
The BBC's Laura Trevelyan, who is travelling with Mrs Obama, says US troops who have been helping with the aid effort are leaving and Haitians are wondering what comes next.
President Obama has previously stated that America will be a reliable partner and will continue to help reconstruction efforts, even though US troops are leaving the area.
About 230,000 people are believed to have died in the quake.
More than a million people lost their homes and many are now living in makeshift camps.
Thousands are being moved to higher ground as the forthcoming rainy season increases the risk of landslides.