The caravan is believed to be preparing to leave Honduras from the city of San Pedro Sula on January 15. It is more than double the size of the previous caravan, which left Honduras in October. Despite only a few hundred migrants starting the long walk, by the time they reached the border in November, more than 7,000 people had joined.
Activists have said the final destination for the new migrant caravan may be Mexico and not the US.
The construction of a new 900 mile railway project is expected to generate thousands of jobs in the south of the country.
Mexican President Andrés Manuel López has pledged to issue visas and employment for Central American migrants.
Karen Spring from The Honduras Solidarity Network, an umbrella group of human rights organisations in the country, said: “It’s possible that many will stay in Mexico, look for work and then try and cross to the US at a later time.
“Ultimately, they are looking for economic security, safety, to be reunited with their families, and overall, a life with dignity.”
Attempts to cross the US border last week by migrants were met with rounds of tear gas by US border guards, many of who haven’t been paid since the Government shutdown started three weeks ago.
Republican firebrand Donald Trump has demanded Congress approve $5.6 billion (£4.4billion) in funding for a wall along the southern US border to be erected, as a solution to stop the influx of people attempting to enter the country.
But Democrats have refused to approve funding for a wall.
They have instead called for increased border security funding.
The disagreement has brought a quarter of the US federal government to a standstill for two weeks because of the failure of Congress and Mr Trump to agree on a new spending package.
Nine government agencies have been impacted including Homeland Security, Justice, State and Treasury.
Around 800,000 federal workers have been made to stay at home or work without being paid since December 22.
But Mr Trump said he was prepared for the partial government shutdown to last years.
He tweeted: “I don’t care that most of the workers not getting paid are Democrats, I want to stop the Shutdown as soon as we are in agreement on Strong Border Security. I am in the White House ready to go, where are the Dems?
“We are working hard at the Border, but we need a WALL. In 2018, 1.7million pounds of narcotics seized, 17,000 adults arrested with criminal records, and 6000 gang members, including MS-13, apprehended. A big human trafficking problem.”