How did the railroads deal with rapidly moving trains across the United States and differences in times ?

American and Canadian railroads begin using four continental time zones to end the confusion of dealing with thousands of local times.

Explanation:

slavery, abortion, donald trump, gay marriage, racial rights, immigration  

explanation:

anything that has been broth up to the supreme court is something of grate political divide   so just look as court cases

1.the population change is near or at replacement level.

4. the birth and death rates are balanced.

6. sweden is most likely a developed country.