Why is an understanding of US foreign policy toward Latin America important to understanding Latin American migration today?

Some observers and commentators have advanced the position that the United States' interventionist policies toward Latin America since the late nineteenth and early twentieth centuries have contributed to instability and poverty in the region. This instability and poverty, they contend, has forced large numbers of residents of Central and South America to flee their native lands.
US entanglement with Latin America traces its roots to American intervention in the Mexican Revolution (1910 to 1920). It later manifested itself in the form of US military occupation of Haiti and the Dominican Republic. However, the Cold-War–era decision of the United States to involve itself in the domestic politics of Latin America has been cited as the most direct inspiration for the current wave of migration. Specific examples of US involvement during this period include the following:
Covert American support for the overthrow of Chilean president Augusto Pinochet,
US support for military dictatorships in Latin America through "Operation Condor,"
American involvement in the Nicaraguan Civil War during the period of the Iran Contra affair.
These, and other, situations—some contend—contributed to regional instability and, through that, chronic poverty.
https://clas.berkeley.edu/research/immigration-latino-migration-and-us-foreign-policy

Because US policies in Latin America are the likeliest contributors to the current mass migrations from those regions, it is critical to understand these policies if we are ever to find solutions to this crisis.
The main reason migrants cite for leaving their countries and entering the US is local violence. Acapulco, for example, has the highest murder rate in the world for any city, mostly perpetrated by drug cartels. The US War on Drugs is considered the cause of much of this violence. Under El Plan Merida, the state department grants $1.2 billion dollars per year to arm and train local law enforcement to fight the cartels; however, local law enforcement is known to be part of the cartel network. This is evidenced by the state-sponsored disappearance of forty-three students from Ayotzinapa in Guerrero in 2014, among others, for example.
The disastrous and bloody civil war in El Salvador was also funded and armed by the US. The brutal Duarte regime was supported by the Reagan administration and the CIA. Effects from this war, including economic instability and violence, continue to trigger migration from this region.
Free-trade agreements, like NAFTA and CAFTA-DR (the North American and Central American Free-Trade Agreements, with the Dominican Republic) are also root causes of mass migration. The privatization and exploitation of local resources displace whole communities. For example, in Mexico and El Salvador, Coca-Cola has displaced tens of thousands by using up and polluting the water supply. US corporations are able to move into areas, like US pharmaceuticals in the Lacandon forests, more freely under these agreements, causing more people to be displaced. NAFTA has also opened the border to sweat shops, with terrible working conditions. When US corporations recruit labor for these border industries in southern Mexico, migrants arrive just to find out these jobs aren’t as promised, and so they are forced to cross the border.