The economic situation encouraged the BNA colonies to unite because of the railways, corn law, and the reciprocity treaty.  The railways encourages the colonies to unite because it makes it easier to transport people and goods to far away places,  and by uniting they would be more likely to get a railway into their colony, but is would not have worked for the island colonies.  The corn laws were restrictions and tariffs on imported grain. They were designed to keep grain prices high to favour domestic producers. This would encourage the colonies to unite because if the law was abolished Canada would have to sell to new customers ( the other colonies ). The reciprocity treaty was a trade treaty between Great Britain and the United States, applying to British possessions in North America which encouraged the colonies to united because Britain could possibly get more from the treaty.