What do frederick douglass' words "america reigns without a rival" mean?

Ahistorian studying urban history in chicago in in the early 1900's. she is studying the population changes and the activities that people did in their everyday lives. based on the description which school of thought does the historian likely belong to

The soviet union and the united states believed in two very different economic systems. what were the names of each?

How did the united states ironically create a slaverybased market economy and democratic political system?