Why was the concept of the city-state an important innovation?

How did the manhattan project to end the war? a scientists working on the project built large bombers. b scientists working on the project discovered uranium. c scientists working on the project developed the atomic bomb. d scientists working on the project shared secrets with axis scientists.

Which areas where seperated by the iron curtain

Which 19th century technological advancement would best allow farmers along the mississippi river in iowa to quickly transport their crops to buyers in louisiana?