Crowds of migrants resumed their long journey north on Sunday from the Mexican border city of Ciudad Hidalgo, according to Mexican federal police officers.
The caravan was headed for Tapachula, a city about 37 km (23 miles) north of the Mexico-Guatemala border, the officers told CNN.
There were about 10 buses awaiting migrants along the highway between Tapachula and Ciudad Hidalgo and the drivers had been instructed to carry the migrants to shelters in Tapachula, the officers said.
One migrant, a 20-year-old Honduran named William, told CNN he crossed into Mexico via a float that carried him across the muddy Suchiate River on Saturday.
He left home looking for work, he said, and was ultimately bound for either Mexico or the US -- wherever he could land a job.
"There is no work back home," he told CNN. "No future."
Thousands of Central American migrants fleeing poverty and violence were initially prevented from crossing a bridge connecting Guatemala and Mexico.
On Friday Mexican authorities began allowing a trickle of migrants, starting with women and children, to pass through the gates and board buses bound for refugee camps.
Others pushed through or climbed over a steel gate before riot police stopped them with tear gas and smoke canisters. Some migrants collapsed, coughing or weeping, according video from the scene.
It's unclear how many migrants were allowed to legally cross the border into Mexico, where they were taken to shelters to rest. On Saturday, with the punishing heat bearing down on them, some migrants took matters into their own hands, and crossed into Mexico on rafts that ferried them across the river.
The caravan formed October 13 in San Pedro Sula, Honduras, and arrived in Guatemala on Monday.
Its slow procession north has prompted US President Donald Trump to threaten to cut aid to Central American nations and to send troops to the US border if Mexico fails to stop the surge.