Question

How was transportation in the 19th century linked to the concept of Manifest Destiny? Transportation improvements such as canals enabled crops to be traded between states more readily, which strengthened ties between North and South. Transportation improvements such as canals led to more exports of perishable goods, which resulted in extending U.S. influence to Canada, Asia, and South America. Transportation improvements such as refrigerated cars allowed for crops to be shipped without spoilage, which fed the Forty-Niners during the Gold Rush. Transportation improvements such as the railroad led to lower prices and easier shipping, which allowed people to expand to the West Coast more easily.

Answer 1

Manifest destiny was that the americans were destined to expand out towards the west and transportation/railroads and stuff allowed the easier access out to the west to start towns/new lives while being able to have some benefits of civilizations. You know, that kind of stuff. 
Manifest destiny is that it is inevitable and destined for americans to spread across the rest of the US continent.