40 years after the Bo’ran invasion, Earth’s major coastlines are inhabited by alien technology. Giant machines so large no one can see the ocean. The invaders are doing something with the water, but no one knows what. Any attempts to learn the purpose of the machines ends in death. Intercontinental trade has been completely stopped. No ships or airplanes can cross the oceans.
North Americans are isolated from the rest of the world. Several civil wars ended 20 years ago. There is no Federal Government, and no United States. Enclaves of humanity survive in effective isolation.
These are some of their stories