Brazil: What aspects in Brazilian history have led to its present mixed ethnic demographics, in contrast to the relatively segregated demographics of the US?

1. Renaissance Portuguese culture, as a whole, was quite tolerant -- if compared with the other contemporary European cultures. 2. Enslaved amerindians and African individuals were not in a position to deny sexual advances by the powerful white colonists, which meant that their women would often bear mixed-race children. 3. Unlike other places, were miscigenated persons were considered lowly, in Brazil it was common for the landowner to have his "bastard" son work close to him, because it is a key feature of Portuguese culture the idea that blood bonds are stronger than any other. Mixed-race people were considered more trustworthy than ameridians and, by far, than Africans. 4. Working close to their white parents, "caboclo" or "mulato" people enjoyed a higher social position and were slowly alienated from their mothers. They eventually evolved as an intermediate class, above the slaves but still below the free men. 5. Miscigenation was the only sure way to be free in a slavist society. Especially black women were eager to bear children by white men so that they could later marry their mixed children to other white mean and ensure that their descendants would not be in danger of slavery. This is superbly shown in this painting by Modesto Brocos, a Spanish artist who lived in Brazil by the end of the XIX century. 6. Miscigenation was a state policy starting from around 1850 until 1946. It was called "branqueamento" (whitening) and foresaw the ideal of supressing black people and making Brazil a white, or mostly white, country. "Branqueamento" involved: a) Displacement of former slaves from the plantations where they had worked, forcing them to relocate to hideouts ("quilombos") in remote areas. b) Replacement of black slaves by European (Portuguese, Italian, German, Spanish, Polish) or Middle-Eastern (Syrians, Lebanese, Egyptians, Turks) settlers. c) Persecution of black culture in all of its aspects. Until 1946, practising Afro-Brazilian religions was a crime, playing capoeira was a crime, writing in the Arabic alphabet was forbidden, Portuguese language was enforced and black people were denied entry in many places. d) A system of colour registration that existed until recently, which included the newborn's "colour" in the birth certificate, but tended to register as "white" every child whose features were not clearly Afro, if the skin was light enough. This increased the perception that black people, by marrying white people, would have "whiter" children, till eventually their descendants would be white. e) Physical elimination of black people, who were more targeted by the police and whose lives were not as eagerly protected. To this day, black people die violent deaths more often than white people. Young black men (16-30) will die by gunshot up to four times more often than white men of the same age. 7. Miscigenation was glorified in Brazilian arts since the inception of national culture, especially literature, but not limited to it. Some famous literary authors advocating miscigenation include Jose de Alencar (late XIX century, whose characters happily love and marry people of other races), Gonçalves Dias (early XIX century, who saw the indigenous element as the most important feature of Brazilian identity), Jorge Amado (mid-XX century, who celebrates miscigenation as the formative process of a true Brazilian identity), Bernardo Guimarães (mid-XIX century, who created the figure of the whitened slave Isaura), Graça Aranha (early XX century, infamous for the pig-eats-baby episode in his novel "Canaan", which is, otherwise, an anthem to the adaptation of German colonists to the tropical landscape of Espirito Santo). 8. Purely European colonies were seen with distrust after the First World War, and the government ever since tried to enforce their "assimilation" forcing them to adopt Portuguese names, stimulating the settling of Brazilians there or forcing their residents to leave for medical assistance or studies, which eventually broke apart the thick isolation of places that preserved German, Italian, Polish or Urkainian dialects in states like Sao Paulo, Rio Grande do Sul, Parana, Santa Catarina, Espirito Santo and Rio de Janeiro. Therefore, despite the social stygmatisation of black people, that makes mixed couples less common than homogenous couples, miscigenation has been very active and has been seen as a positive change of the overall society.

The two biggest reasons are: Miscegenation Due to the harsh travel climates from Portugal to Africa then to Brazil, most of the Portuguese colonizers settled Brazil by themselves without their wives or families. Human nature reigns supreme, even over racism. Portuguese men began “relationships” with African women and created a mixed racial class. This was called http://en.wikipedia.org/wiki/Miscegenation. The mixed class in Brazil were treated slightly better than full blacks, receiving educational and job opportunities not permitted to slaves. Despite this, certain Brazilians, including some Afro-Brazilians, believe Brazil was and still is less racist than other slave-holding countries due to the heavy mixing. The infamous doctrine of having a “racial democracy”  began when a few Brazilian historians compared their slavery to other slave countries like the United States. Despite less segregation in Brazil, they were the last country in the Americas to abolish it in 1888. White Immigration After slavery, Brazil was heavily black. This troubled the white Brazilian government, so they began to advertise Brazil to the poor classes in Europe who wanted a new start in life. During the late 19th century, Brazil began to “whitened” its country through white immigration. Brazil didn’t only have hopes of increasing the European descended population; they wanted these new white-Brazilians to also continue the legacy of miscegenation. The mixing of races continued. White Brazilians, especially men, continued to have children with black women, even if they had a family already. Many Afro-Brazilian families advised their children to date white-Brazilians to “lighten the family” and give their family more life opportunities. http://www.rioinaweek.com/the-different-shades-of-black-in-brazil/

The  social economics were quite different in different places. Spaniards tended to  convert local populations to serfs and had no qualms about sexual  interactions with them, probably for the reasons stated above. The result was a single albeit unequal society with somewhat murky racial distinctions.* Colonists in Brazil or the Caribbean had an economy based on very profitable but  labor intensive sugar production. For this reason they often enslaved the local populations as the Spaniards did, but also imported a great number of African slaves to remain productive. These societies also tended to experience racial mixing and inequality that survives to this  day, but nonetheless brought everyone into the same social structure. In  North America by contrast, at least North of Virginia, plantations were  much less viable as an economic driver, and much of the economy was  fueled by the Fur Trade with the Native Americans, some export of raw materials such a lumber, and subsistence agriculture. Because there was much less need for a large workforce, and because England was so poor at the time that people were quite ready to emigrate, there was no economic incentive to enslave the native populations or integrate them into colonist societies. At the same time, as colonists settled on land once home to Native Americans cultural differences, difficulty in communication, and outright land grabs provoked violence, especially in English settled areas, which tended to have more colonists and less tolerance for their neighbors than the French or Dutch. As the English colonies consumed the Dutch (New York) and French (Canadian) colonies, their cultural attitude towards the Natives as violent savages became the prevailing one. Even after USA's separation with England, we carried on their tradition of kicking the locals off their land through force and never really integrated them into colonial society. * aside: The   Spanish colonies were so vast that they had no hope of peopling them  with Spaniards. so in order to maintain control it was decided that the  locals needed to be converted to Catholicism which would make them loyal  to the king of Spain. Charles V controlled most of Europe and was crowned by the pope, implying Hell and eternal damnation for anyone foolish enough to revolt. This is reflected in the efforts of Spaniards to convert and assimilate the conquered peoples.

This might only be a part of it, but one explanation I've heard for this is that Latin America was largely colonized by single European men (soldiers, government officials, adventurers, etc.) as opposed to North American settlers who came with their families. This lead to more racial mixing in Latin America (though it remained deeply racist when it came to social standing) and clearer boundaries between ethnicities in North America.