The migrants, who have drawn near-daily Twitter tirades from US President Donald Trump, walked and hitched rides from the town of Huixtla, in southern Mexico, to Mapastepec, some 60 kilometers away.
Carrying their few belongings on their backs, many with babies pressed to their chests or holding their children by the hand, they left at dawn after taking a one-day break to rest, bathe and nurse aching and injured feet.
"I miss my country. I'm not doing this because I want to. No one wants to leave their home to go to a place they don't know. But sometimes necessity pushes us to do this, because of what's happening in our countries," said Delmer Martinez, a migrant from El Salvador.
Determined to reach US border
Fleeing violent crime, political unrest and poverty at home, the migrants say they are determined to reach the United States, despite Trump's vows to stop them, and his threats to cut aid to Central American countries, as well as to deploy the military and close the southern US border.
There are now about 7,000 migrants in the caravan, the United Nations estimates, though Mexican authorities put the number much lower: 3,630.
Masses of migrants moving towards the US border. Source: Getty Images
The vast majority are from Honduras.
In a show of solidarity, Mexicans watching the caravan pass shouted out, "Keep it up, brothers!" and gave them food and water.
"Mexico! Mexico!" the migrants shouted in reply, bathed in sweat under the hot sun of the southern state of Chiapas.
They have so far traveled about 100 kilometers from the Mexico-Guatemala border, where they crashed through a series of border gates last Friday.
Halted at the final gate by hundreds of riot police, most of the caravan entered Mexico by swimming or taking rafts across the river that forms the border.
Mexican federal police have periodically accompanied the caravan in trucks or flown overhead in helicopters, but without attempting to stop it.
According to the Mexican government, about 1,700 people who were traveling in the caravan have requested asylum in Mexico.
The migrants still have some 3,000 kilometers left to walk to reach the US.
