Why are so many migrants here in the first place?
The question is being asked from the US perspective. While immigration to the US is not just from Latin America, there is clearly where the big numbers come from. Many articles try to justify immigration by saying "we need them". Maybe the US does -- or the price of California lettuce would go up -- but that doesn't address why they see the US as the land of opportunity.
An article in Truth-Out tosses in enough history so you can put the pieces together. You may not like where the article leads.
To understand this situation, it’s helpful to start with El Salvador’s 12-year civil war, which was to become the most costly U.S. intervention in Latin America.
The United States spent $1 million a day funding death squads and a far-right military government in efforts to ward off the spread of communism and “another Nicaragua.” As a result, the country was traumatized by massive human rights violations and the death of 75,000 people. But perhaps what really tipped the scales was the formation of U.S.-funded private development organizations like FUSADES, which furthered neoliberal programs inside the country. The United States has also meddled in elections and set preconditions for U.S. aid that incentivizes — one might say bribes — politicians to open up the country to foreign multinationals. The recent enactment of the public-private partnership law, for example, grants “the government the right to sell off natural resources, infrastructure and services to foreign multinationals.”