What caused economic tensions between the North and South since they both had different economies

The issue of slavery caused tension between the North and the South. ... Some Northern workers and immigrants opposed slavery because it was an economic threat to them.

Explanation: hopes this helps

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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:

1. temperance, abolitionist, suffragist