In the Americas, the confluence of multiple ethnic groups from around the world contributed to multi-ethnic societies. In Central and South America, most people are descended from European, Amerindian, and African ancestry. In Brazil, where in 1888 nearly half the population descended from African slaves, the variation of physical characteristics extends across a broad range. In the United States, there was historically a greater European colonial population in relation to African slaves, especially in the Northern Tier. There was considerable racial intermarriage in colonial Virginia, and other forms of racial mixing during the slavery and post-Civil War years. Jim Crow and anti-miscegenation laws passed after the 1863–1877 Reconstruction era in the South in the late-19th century, plus waves of vastly increased immigration from Europe in the 19th and 20th centuries, maintained much distinction between racial groups. In the early-20th century, to institutionalize racial segregation, most southern states adopted the "one drop rule", which defined and recorded anyone with any discernible African ancestry as "black", even those of obvious majority native European or of majority-Native-American ancestry.