Brazil is the largest and most populous country in Latin America. In 1980, the census bureau counted nearly 120 million people, a figure more than twice that of second-ranked Mexico. Brazil's 8.5 million square kilometers of national territory stretch from the Atlantic Ocean in the east to the foothills of the Andes in the west; from the Guiana plateau in the north to the Plate River basin in the south. The country's continental proportions dominate the geopolitical map of the southern hemisphere, making it the fifth largest country in the world, surpassed in area only by the Soviet Union, the United States, China and Canada.

In the nineteenth century, the change from colony to independent empire (1822), from monarchy to republic (1889–91) and from slaveholding society to a free one (1888) occurred essentially without violence. Brazil's early history thus imparted to the country a legacy of political stability and national unity rare in the New World (Burns 1970). Unlike many of its neighbors in the continent, direct military control of the state has been the exception in Brazil. From the late 1800s through the first three decades of the twentieth century, Brazil's presidents were duly elected. The democratic tradition was interrupted in the period 1930–4 and again in 1937–45 when Getulio Vargas, a civilian backed by the military, ruled by decree.