Definición de imperialismo

El imperialismo (generalmente en forma de un imperio) —que se basa en ideas de superioridad​ y aplicando prácticas de dominación— es el conjunto de prácticas que implican la extensión de la autoridad y el control de un Estado o pueblo sobre otro.

During the 1800s due to an economic and military weakness of the U.S compared to its neighbors the British, French and European rivals, the United States foreign policy makers sought diplomatic means to counter European presence. 
The U.S diplomacy aimed at preventing France and Britain from accessing the control of more colonies in Latin America and Mexico which were a part of a declining Spanish empire. 
Foreign policy goals previously focussed on gaining colonies and expansion to new territories, but, changed to developing commercial empires, limit the influence o the Soviet (USSR) and encourage more significant economic and political freedom.