Which had the biggest effect on civil rights for all united states citizens

It was the "The Black Codes" which were laws in the United States after the Civil War with the effect of limiting the civil rights and civil liberties of blacks.

Explanation:

c, they united with once

2686-2181 bce-- "egyptian civilization developed along the nile river in large part because the river’s annual flooding ensured reliable, rich soil for growing crops."

1069-664 bce-- "ancient egyptians developed wide-reaching trade networks along the nile, in the red sea, and in the near east."