A migrant girl from Honduras, part of a caravan of thousands traveling from Central America en route to the United States, cries after running away from tear gas released by U.S. Customs and Border Protection (CBP) agents near the border wall between the U.S. and Mexico in Tijuana, Mexico, November 25, 2018.

A photojournalist is surrounded in a cloud of tear gas released by U.S. Customs and Border Protection (CBP) agents after migrants, part of a caravan of thousands from Central America, attempted to illegally cross the border into the United States from Tijuana, Mexico, November 25, 2018.

Migrants, part of a caravan of thousands from Central America trying to reach the United States, return to Mexico after being hit by tear gas by U.S. Customs and Border Protection (CBP) after attempting to illegally cross the border wall into the United States in Tijuana, Mexico, November 25, 2018.

A migrant girl, part of a caravan of thousands from Central America, sits on top of her father's shoulders as they are surrounded by police while marching to the United States border in Tijuana, Mexico, November 25, 2018.

Migrants, part of a caravan of thousands from Central America trying to reach the United States, make their way to the border fence between Mexico and the United States in Tijuana, Mexico, November 25, 2018.

Migrants, part of a caravan of thousands traveling from Central America en route to the United States, climb a wall to evade police and reach the border between the U.S and Mexico in Tijuana, Mexico, November 25, 2018.

Migrants, part of a caravan of thousands from Central America trying to reach the United States, walk near the border fence between Mexico and the United States in Tijuana, Mexico, November 25, 2018.

Migrants, part of a caravan of thousands traveling from Central America en route to the United States, cross the Tijuana river to reach the border wall between the U.S. and Mexico, November 25, 2018.

Migrants, part of a caravan of thousands traveling from Central America en route to the United States, take part in a protest march towards the border wall between the U.S. and Mexico, in Tijuana, Mexico, November 25, 2018.

Honduran migrants leave Guatemala City on October 18, 2018, heading in a caravan to the United States.

A caravan of about 2,000 Honduran migrants set out on October 13 from the impoverished, violence-plagued country for the long journey through Guatemala and Mexico to the U.S. border. The numbers have grown to at least 7,200, the largest such group ever. President Trump warned Honduras he will cut millions of dollars in aid if the migrants are allowed to reach the United States.

A man, part of a caravan of migrants from Central America en route to the United States, carries a girl through the Suchiate River from Guatemala into Ciudad Hidalgo, Mexico, October 29, 2018.

Migrants rest in a makeshift camp in Santiago Niltepec, Mexico, October 29, 2018.

The U.S. is deploying at least 5,200 troops to the U.S.-Mexico border area.

Migrants stand in front of the fortified border gate between Guatemala and Mexico, in Tecun Uman, Guatemala, October 29, 2018.

Migrants, traveling in a caravan from Central America en route to the United States, walk along the highway to Juchitan from Santiago Niltepec, Mexico, October 30, 2018.

The journey is expected to take many weeks.

Migrants make a human chain to pull people from the river separating Guatemala from Ciudad Hidalgo, Mexico, October 29, 2018. 

Honduran migrants walk behind the Honduran flag in a caravan towards the United States in Chiquimula, Guatemala, on October 17, 2018.

Most of the travelers tell CBS News they are fleeing extreme poverty, but the U.S. does not grant asylum or refugee status for people seeking economic opportunity. Some also say gang violence prompted them to flee their homes.

Honduran migrants aboard vehicles headed towards the United States, in Guatemala City, on October 18, 2018.

Once the caravan reached Mexico, Mexican officials say at least 1,743 applied for permission to stay there rather than continue on to the U.S.

Honduran migrants cross the border from Guatemala into Mexico on October 19, 2018.

Mexican Federal Police officers get ready for the arrival of a caravan of Honduran migrants heading to the U.S., on the international bridge in Ciudad Hidalgo, Mexico, on the border with Guatemala, on October 19, 2018. 

Honduran migrants heading in a caravan to the U.S. remove a barrier at the Guatemala-Mexico international border bridge in Ciudad Hidalgo, Mexico, on October 19, 2018. 

President Trump has threatened to cut aid to Central America over the migrants. Last year, the U.S. sent more than $300 million in foreign aid to Honduras, Guatemala and El Salvador.

A woman holds a crying baby as Honduran migrants heading in a caravan to the U.S. are met by Mexican police at the gates of the Guatemala-Mexico international border bridge in Ciudad Hidalgo, Mexico, on October 19, 2018.

Men attempt to grab a tear gas canister thrown by the Mexican Federal Police, after Central American migrants rushed the gate at the border crossing in Ciudad Hidalgo, Mexico, on October 19, 2018. 

A youth calls for calm as he stands in front of a line of Mexican Federal Police in riot gear, after Central American migrants rushed the gate at the border crossing in Ciudad Hidalgo, Mexico, October 19, 2018. 

A Honduran migrant is cooled down after struggling to cross one of the gates of the Guatemala-Mexico international border bridge in Ciudad Hidalgo, Mexico, on October 19, 2018.

A Honduran migrant mother and child cower in fear as they are surrounded by Mexican Federal Police in riot gear, at the border crossing in Ciudad Hidalgo, Mexico, October 19, 2018. 

Central Americans traveling in a caravan broke through a Guatemalan border fence and streamed by the thousands toward Mexican territory, defying Mexican authorities' entreaties for an orderly migration and U.S. President Donald Trump's threats of retaliation.

Honduran migrants heading in a caravan to the U.S. lift a child over the gate of the Guatemala-Mexico international border bridge in Ciudad Hidalgo, Mexico, on October 19, 2018.

Aerial view of a Honduran migrant caravan stopped on the Guatemala-Mexico international bridge in Ciudad Hidalgo, Chiapas state, Mexico, on October 19, 2018.

The group is more than four times larger than the caravan of about 1,500 Central American migrants who reached the U.S.-Mexico border in April 2018. Of those 1,500, only about 250 legally remained in the U.S. six months later pending an immigration hearing, according to Pueblos sin Fronteras, a humanitarian aid organization for migrants.

A Honduran migrant family is allowed to pass through to safety by Mexican Federal Police in riot gear, at the border crossing in Ciudad Hidalgo, Mexico, on October 19, 2018. Central Americans traveling in a caravan broke through a Guatemalan border fence and streamed by the thousands toward Mexican territory.

Thousands of Honduran migrants rush across the border towards Mexico, in Tecun Uman, Guatemala, October 19, 2018. Migrants broke down the gates at the border crossing and began streaming toward a bridge into Mexico. 

Mexican Federal Police officers try to block Honduran migrants from going through at the Guatemala-Mexico international border bridge in Ciudad Hidalgo, Mexico, on October 19, 2018. 

Thousands of Honduran migrants rush across the border towards Mexico, in Tecun Uman, Guatemala, on October 19, 2018. Migrants broke down the gates at the border crossing and began streaming toward a bridge into Mexico.

Migrant women and children rush onto the bridge between Guatemala and Mexico after pushing past Guatemalan police on October 19, 2018. 

Honduran migrants heading in a caravan to the U.S. arrive in Ciudad Hidalgo, Mexico, aboard a makeshift raft after crossing the Suchiate River, the natural border between Guatemala and Mexico, on October 20, 2018.

Honduran migrants heading towards the United States rest at a gymnasium of a Catholic church in Chiquimula, Guatemala, on October 16, 2018. 

Honduran migrants aboard a pick-up van heading to the United States  under heavy rain in Siquinala municipality, south of Guatemala City, on October 18, 2018.

Honduran migrants line up to receive food after arriving in Mazatenango, 160 km south of Guatemala City, on October 18, 2018.

Migrants heading in a caravan to the United States walk with a Honduran national flag as they leave Guatemala City, on October 18, 2018.

Honduran migrants stop to rest at a gas station in Zacapa, Guatemala, on October 16, 2018. 

Honduran migrants walk across the Guatemala-Mexico international border bridge, from Guatemala's Ciudad Tecun Uman to Mexico's Ciudad Hidalgo, on October 19, 2018.

Honduran migrants rest in Ciudad Tecun Uman, Guatemala, near the border with Mexico, on October 19, 2018. 

To obtain asylum in the U.S., migrants will have to prove they have a credible fear of harm if they return to their home country. Economic hardship is not an acceptable reason.

A Honduran migrant heading to the United States reads the New Testament as he rests at the Casa del Migrante (Migrant's House) in Guatemala City on October 17, 2018. 

A Honduran migrant wearing a "Donald Trump for President" t-shirt walks across the Guatemala-Mexico international border bridge, from Guatemala's Ciudad Tecun Uman to Mexico's Ciudad Hidalgo, on October 19, 2018.

Honduran migrants, heading in a caravan to the United States, argue with Guatemalan police officers at the border with Mexico, on October 19, 2018. The previous day, President Trump threatened to close the southern U.S. border if Mexico fails to stem what he called the "onslaught" of migrants from Central America.

Honduran migrants, heading in a caravan to the United States, gather at the central park of Ciudad Tecun Uman, Guatemala, near the border with Mexico, on October 19, 2018.

Honduran migrants aboard a truck heading through Guatemala towards the border with Mexico on October 19, 2018. 

Honduran migrants sleep on the floor at Tres Caidas Church in Tecun Uman, Guatemala, near the border with Mexico, on October 18, 2018.

Honduran migrants get on a car to go to Tecum Uman, on Guatema's border with Mexico, in Guatemala City, on October 18, 2018.

Honduran migrants heading in a caravan to the U.S. cross the Suchiate River in a makeshift raft in Ciudad Tecun Uman, Guatemala, on October 19, 2018. 

Honduran migrants heading in a caravan to the U.S. open one of the gates of the Guatemala-Mexico international border bridge in Ciudad Hidalgo, Mexico, on October 19, 2018. 

The U.S. is deploying at least 5,200 troops to the U.S.-Mexico border area.

Honduran migrants walk across the Guatemala-Mexico international border bridge on October 19, 2018. 

Honduran migrants, including a man pushing a baby carriage, walk across the Guatemala-Mexico international border bridge on October 19, 2018.

Honduran migrants heading in a caravan to the United States rest in a park in Tecun Uman, Guatemala, on the border with Mexico, on October 18, 2018. 

Honduran migrants wave from a vehicle on their way to Tecun Uman, Guatemala, on the border with Mexico, as they take part in a caravan heading to the United States on October 19, 2018.

A Honduran migrant, heading in a caravan to the United States, holds a sign reading, "Donald Trump, we are not criminals, we are workers who want to work," in Tecun Uman, Guatemala, on October 19, 2018.

A Honduran boy cries after his mother decided he wouldn't accompany her across the Goascoran River - the border between Honduras and El Salvador - since its current is too strong, on October 18, 2018.

A Honduran migrant prepares to cross the Goascoran River to enter illegally into El Salvador, on October 18, 2018. 

A Honduran migrant prepares to cross the Goascoran River to enter illegally into El Salvador, on October 18, 2018.

A Honduran migrant woman walks next to her son as she prepares to cross the Goascoran River to enter illegally to El Salvador on October 18, 2018.

Honduran migrants attempt to cross the Goascoran River to enter illegally to El Salvador on October 18, 2018.

Honduran migrants, part of a caravan heading to the United States, stop to eat in Guatemala on October 18, 2018.

A Honduran migrant woman helps a boy at the main square of Ciudad Hidalgo, in Chiapas state, Mexico, on October 19, 2018.

Honduran migrants cross the border from Guatemala into Ciudad Hidalgo, Mexico, on October 19, 2018.

Honduran migrants heading to the U.S. get cups of coffee at the main square of Ciudad Hidalgo, Mexico, on October 19, 2018.

A Honduran migrant heading to the U.S. rests at a temporary shelter in Ciudad Hidalgo, in Chiapas state, Mexico, on October 19, 2018.

Honduran migrants attempt to cross the Goascoran River from Honduras into El Salvador on October 18, 2018. 

Honduran migrants rest in the main square of Ciudad Hidalgo, Mexico, on October 19, 2018. 

Honduran migrants sleep on the ground in Chiquimula, Guatemala, on October 17, 2018. 

Honduran migrants crowd into a truck in a caravan to the United States, in Guatemala City, on October 18, 2018.