I would say that Plessy v. Ferguson contributed to the Civil Rights movement. This was a court case that ruled that racial segregation in schools was allowed as long as the education for black students was equal to white students. Although this does not seem like a civil rights act, it later lead to Brown v. Board of Education, which ended racial segregation in schools all together.
Greek artists included the ideas of reason, moderation, balance, and harmony in their works because they hoped that their art would inspire people to base their lives on these same ideas.
Cahokia was one of the largest and possibly the capital city of the people that are referred to as the Mound Builders. Cahokia's size and the large number of people that lived there led to the main issues. Bad droughts and poor harvests meant people couldn't eat.