Why did independent greek city states develop instead of a single state covering the entire greek peninsula

Write the title date and stated purpose of the map you have chosen to describe what you learn from your careful review of the maps information. picture above

How did the completion of the transcontinental railroad change the lives of american citizens? a-it increased the wealth of all americans and enabled them to travel more. b-it made cross-country travel too expensive for ordinary americans. c-it decreased the safety of americans who moved to settle the plains. d-it shortened travel time between the east and west for all americans.

What was the overall impact of eli whitneys introduction of interchangeable parts?