forming an important part of Puerto Rican culture and society. Recent black immigrants have come to Puerto Rico, mainly from the Dominican Republic, Haiti, and other Latin American and Caribbean countries, and to a lesser extent directly from Africa as well. Many black migrants from the United States and the Virgin Islands have moved and settled in Puerto Rico. Also, many Afro–Puerto Ricans have migrated out of Puerto Rico, namely to the United States. There and in the US Virgin Islands, they make up the bulk of the U.S. Afro-Latino population. Under Spanish and American rule, Puerto Rico underwent a whitening process. Puerto Rico went from around 50% of its population classified as black and mulatto in the first quarter of the 19th century, to nearly 80% classified white by the middle of the 20th century. Under Spanish rule, Puerto Rico had laws such as Regla del Sacar or Gracias al Sacar, which classified persons of mixed African-European ancestry as white, which was the opposite of "one-drop rule" in US society after the American Civil War. Additionally, the Spanish government's Royal Decree of Graces of 1815 encouraged immigration from other European countries. Heavy European immigration swelled Puerto Rico's population to about one million by the end of the 19th century, decreasing the proportion Africans made of Puerto Rico. In the early decades under US rule, census takers began to shift from classifying people as black to "white" and the society underwent what was called a "whitening" process from the 1910 to the 1920 census, in particular. During the mid 20th century, the US government forcefully sterilized Puerto Rican women, especially non-white Puerto Rican women. Afro–Puerto Rican youth are learning more of their peoples' history from textbooks that encompass more Afro–Puerto Rican history. The 2010 US census recorded the first drop of the percentage whites made up of Puerto Rico, and the first rise in the black percentage, in over a century. Many of the factors that may possibly perpetuate this trend include: more Puerto Ricans may start to identify as black, due to increasing black pride and African cultural awareness throughout the island, as well as an increasing number of black immigrants, especially from the Dominican Republic and Haiti, many of whom are illegal immigrants, and increasing emigration of white Puerto Ricans to the mainland US. The following lists only include only the number of people who identify as black