The following that was an effect of segregation in cities in the late 1800s: the formation of enclaves, by being surrounded by a larger whose inhabitants are culturally or ethincally distinct. The 1800s was charactirized by the arrival of many immigrants to the United States. Therefore it led to immigrants moving to the suburbs to creating enclaves.
The United States contributed to the conflict by providing military aid of $1–2 million per day to the government of El Salvador during the Carter and Reagan administrations and provided significant training. The Salvadoran government was considered "friendly" and an ally by the U.S. in the context of the Cold War.