Explain how canals overcome geographical obstacles hills , mountains?

I believe it would be because it runs through the Earth, saving you more time and energy compared to climbing/scaling a hill/mountain

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:

a. by accepting the election of president abraham lincoln in 1860 and convincing other southern states to do the same