A movement from one place to another, The Great Migration refers to the movement in large numbers of African Americans during and after World War I from the rural South to industrial cities of the Northeast and Midwest. One million people left the fields and small towns of the South for the urban North during this period (1916-1930).
The period of peace and prosperity in the Roman Empire is known as the "Pax Romana," since this is what translates roughly to Roman Peace in Latin.
The manual labor system would complete collapse and we would fall in our economy therefore giving us a useless currency.