Brazil, the largest country in South America and the only Portuguese-speaking country in the Americas, was a Portuguese colony from the early 16th century until the early 19th century, when it achieved independence from Portugal. To the late 19th century it finally became a republic. Brazil is the largest national economy in South America and the sixth largest in the world. It has large and developed agricultural, mining, manufacturing and service sectors, and huge amounts of oil reserves. The economic rise of Brazil is associated with the policy, as well as in most of countries in the world. Thus, the economic rise of Brazil began in the mid 1950s, and has been constantly developing, leading to the fact that Brazil became one of the world's leading economic powers in the early 2000s, and it remained so to this days. Brazil owes its economic development primarily to great natural resources which it possesses, primarily being agricultural land and large oil fields. Brazil is a member of many regional and international organizations. Over the past 15 years Brazil has become a regional economic power which is slowly replacing the United States, and thus creating tensed relations between the two countries. Despite all the economic successes, there are still huge socio-economic inequalities in Brazil which the population is difficult to accept, however the government is trying to reduce this inequalities in various ways.