Desegregation is the process of ending the separation of two groups, usually referring to races. Desegregation is typically measured by the index of dissimilarity allowing researchers to determine whether desegregation efforts are having impact on the settlement patterns of various groups. This is most commonly used in reference to the United States. Desegregation was long a focus of the Civil Rights Movement, both before and after the United States Supreme Court's decision in Brown v. Board of Education, particularly desegregation of the school systems and the military (see Military history of African Americans). Racial integration of society was a closely related goal.