A biggie: the transcontinental railroad. Because it would economically improve wherever it was, both the North and the South competed for the railroad to be in their respective territory, evidenced by the Kansas-Nebraska Act and the Gadsen Purchase and induction of California as a free state in 1860. 
In addition: people could get land cheap because it was abundant and might leave to start afresh economically.
There's other stuff I can't remember as clearly, but there's a little and I hope it helps :)
        
             
        
        
        
Answer: Polar bears eat arctic cod
Arctic cod eats two type of zooplankton
        
                    
             
        
        
        
Answer:
Degrees east and west of the prime meridian are measured by boundaries is the longitude. 
 
        
                    
             
        
        
        
2- East Germany and West Germany
West-the USA, Britain and France
East- Soviet Union
        
             
        
        
        
<span>paint a picture in the reader's mind.</span>