The caravan brings together mothers from El Salvador, Guatemala, Honduras and Nicaragua.
They cross the border between Guatemala and Mexico on inflatable rafts to symbolise the risks the migrants face when crossing into Mexico.
They then travel together across Mexico in search of their relatives who disappeared.
In the 13 years since the caravan was first organised by the Mesoamerican Migrant Movement, 270 missing migrants have been located.

Part of the idea behind the caravan is also to denounce and highlight the issue of disappearances of migrants in transit through Mexico.

Of the 270 missing migrants who have been found, 90% are men. Women are much harder to find, especially when they have been forced into the sex trade. In order to boost their chances of finding those women, the movement has forged links with organisations run by sex workers.

They place pictures of the missing migrants in brothels in the hope someone will recognise their loved ones.

Clementina Murcia González has been part of the mothers' caravan for the last five years. Two of her sons went missing: Jorge in 1984 and Mauricio in 2001.

With the help of a a local radio station, Radio Progresso, she recently managed to track down Mauricio and will be reunited with him in the Mexican city of Guadalajara as part of this year's caravan.

"Sixteen kisses and 16 hugs is all I want from my son," she says about the impending reunion.

Her search for Jorge continues.

Along the way, the caravan meets local communities. In La Ceiba, a cultural and educational centre working with indigenous communities in Chiapas, the mothers are invited to a Mayan ceremony, a pre-hispanic ritual to connect with ancestors.

Source: BBC