Explain how political changes in the period from c. 1900 to the present led to territorial, demographic, and nationalist developments.

the question is asking about the things that may have affected and what they effects had on the spanish conquest and settlement of america

explanation:

answer: the time zones used to be whatever the local authority wanted them to be. one town might have 6am whenever the sun came up and another town had 6am 10 minutes later.  

the trains had a hard time when their orders said to be at a certain point at 6am.  

6am, but who's 6am.  

the railroads got together and set the time zones more or less along the longitude lines across the country.

explanation:

ok i will try

explanation: