(CNN) The agony and desperation are written all over the migrants' faces. But what you can't see is how bad their homelands really are.
Why would a caravan of migrants spend a month trekking across several countries, battling hunger, filth and illness, when their chances of getting US asylum are so slim?
A snapshot of the countries they're fleeing from shows the nightmares they're trying to escape:
Gross national income, per capita: $2,150
Population living in poverty: 60.9%
Life in Honduras: As the second-poorest country in Central America, Honduras "suffers from extraordinarily unequal distribution of income," and rampant underemployment, the CIA World Factbook says.
Widespread gang violence fuels the instability and suffering. Criminals have extorted Hondurans into paying an arbitrary "war tax" for their survival, and those who can't pay often are killed.
"There are no jobs, no justice, no laws in Honduras," said 32-year-old Karen Gallo, one of the migrants on the caravan.
Some of the migrants are transgender people who faced persecution in Honduras. Nikolle Contreras said she suffered "discrimination because of my sexuality, lack of work, discrimination within my own family for being gay and worse, for being a trans person."
Gross national income, per capita: $3,920
Population below poverty line: 38.2%
Life in El Salvador: "El Salvador is beset by one of the world's highest homicide rates and pervasive criminal gangs," the CIA World Factbook says.
One 38-year-old migrant on the caravan said she understands not everyone will welcome her to the US.
"But I don't have an option," she told CNN. "If I stay in El Salvador, I'm going to be killed."
In recent decades, poor economic conditions and natural disasters also have contributed to Salvadorans fleeing to the United States.
Gross national income, per capita: $3,790
Population below poverty line: 59.3%
Life in Guatemala: Almost half of Guatemalan children under age 5 are chronically malnourished -- "one of the highest malnutrition rates in the world," the CIA World Factbook says.
"Guatemalans have a history of emigrating legally and illegally to Mexico, the United States and Canada because of a lack of economic opportunity, political instability, and natural disasters."
More than half of the country lives in poverty, and 23% lives in extreme poverty -- meaning people live on less than $1.25 a day.