Even before the U.S really started projecting itself in Latin America, the social and political divides left Latin American countries divided politically and socially.

The Spanish were kicked out, but the social system of European elites remained along with the mercantist style plantation systems and mines. When the Spanish left, the colonial elite, in broad strokes, did all they could to maintain their political and economic power, and they often allied with the other traditional standing power: the Catholic Church. Thus in many of these countries, despite receiving independence, the economic and social structures remained relatively unchanged, and this spawned a constant upbringing of reformers, revolutionaries and other opportunists who took advantage of the fact that the majority of the people in these countries were disenfranchised.

From independence until even today the social conflicts played out as revolutions, civil wars and unrest constantly occurred. For more in depth research, look no further than the constant revolutions in Nicaragua, the continual military coups in Colombia and the brutal Mexican Civil and Christero war.

As for the exact degree to which the U.S was responsible in pushing unrest and causing calamity in these countries, I am uncertain to say. But U.S caused massive turmoil in its constant meddling in Nicaragua, Panama and elsewhere. The U.S depended on Central America and elsewhere for a cheap and plentiful supply of coffee, bananas and other products, and it promoted strongmen like Somoza of Nicaragua who would ensure complete American domination of the market in exchange for keeping power.

Once the Cold War came, meddling in central and South America became more than just trying to benefit th U.S economically. Democracies across Latin America were thrown into chaos by U.S backed coups and right wing strongmen were strengthened even if their policies were detrimental to their country's economic health.

The total economic impact of U.S meddling, is again, hard to quantity, but you only need to look at the economic progress that many former "banana republics"have made as the U.S has stopped fighting an ideological war there and has generally only used soft power to influence the region. Granted, many countries for their own reasons (Venezuela) still face problems, others face the scars of U.S intervention(Nicaragua) and still others like Honduras and Colombia face problems and meddling from the U.S due to U.S drug policy. "edited for basic grammar mistakes on tablet"