At the Worthwhile Canadian Initiative blog, Livio Di Matteo explains one of the less mentioned but urgent reasons behind confederation in 1867:
The trials and tribulations of the European Union, its debt crisis and the Euro and the suggestion that part of the solution lies in a stronger fiscal union reminds me of the forces behind the drive for Canadian confederation in the mid-nineteenth century. Canadians are usually taught in school that major forces driving Confederation were the potential threat of territorial aggrandizement by the United States in the wake of the Civil War or the need for a larger market given Britain’s move to free trade and the end of Reciprocity with the Americans or the desire to generate the economic resources to build a railway to the west so that it could serve as an investment frontier.
One factor that receives very little mention is the fact that the prior to 1867 the colonies of British North America were heavily in debt and faced a fiscal crisis of their own. The solution to the colonial debt crisis that Confederation allowed was the creation of the federal government that was given strong revenue raising powers and assumed provincial debts and thereby stabilized the public credit. Public debt charges in 1867 already accounted for 29 percent of federal budgetary expenditure and by 1880 had only been whittled down to about 24 percent. Canada was born in debt.
Canada was created with a large debt as the provincial and local levels of government had invested heavily in transportation infrastructure — canals and railways in particular. In 1850, there were only about 66 miles of track in operation but by 1860 about 2000 miles of track had been built in eastern Canada. The total cost of building these railways in British North America up to 1867 was 145.8 million dollars the bulk of which was for the Province of Canada — Ontario and Quebec. By way of comparison, Canada’s GDP in 1870 has been estimated at about 383 million dollars.
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Confederation was designed to fix a massive debt problem. Creation of a new political entity — the dominion government — would allow for the current debt burden to be serviced and for more credit to be obtained on foreign markets to fund the railway projects of the late 19th century — the CPR, Canadian Northern, etc… Confederation was a solution to the debt crisis but required a form of government that reduced sovereignty for the member units in order to stabilize the public credit. In the Canadian case, as acrimonious as the discussions were, the process was facilitated by the fact that the member units were all British colonies with similar institutions.