What Enlightenment idea was so important that Locke, Voltaire, Rousseau, and other philosophes wrote about?

What triumphs did the late 19th century witness in the realms of industrial growth, urbanization, and technological innovation? what challenges did these developments pose for urban dwellers, workers, and recent immigrants? how did city officials and everyday citizens respond to these challenges?

About how many european immigrants were processed at the facilities on ellis island

What has been a long term effect on the panama canal