Starting in the early 1800’s, Spain’s Latin American colonies all began to revolt. The combination of Spain’s decline as a global power and the spread of Enlightenment ideals contributed to the rise of revolutionary fervor in many Latin American countries.
These revolutions had many things in common. First, many of them were populist movements (started by common people) but led by a single, charismatic individual. In Mexico it was Father Hidalgo, in Columbia it was Simon Bolivar. In Argentina it was revolutionary Jose de San Martin.
Also, all these revolutionaries borrowed heavily from the American Revolution. Some of them took ideas from out own Constitution while others adopted our Declaration of Independence.
All of these movements were to some extent protected by the U.S. when the Monroe Doctrine was adopted. The U.S. decided to protect all the newly minted countries from further European colonization when it passed this law.