It's interesting how prosperous Halifax looks in photos from the mid-late 1800s period. The gate looks like something from a European city and the ice rink was the first in Canada. One of the institutional buildings in the background of that photo was an exhibition hall. I'm not sure what the other brick building farther off in the distance was -- maybe the poor house, but I thought it had burned down by then.
Back around 1870 Halifax was more like, say, Calgary is today. Atlantic Canada had about 1/4 of Canada's total population. By 1930 or so Halifax had fallen to the point where it was about the same size as places like London, Ontario. Since then it has been a medium-growth city. This sort of growth timeline is pretty unique in North America; the industrial cities did amazingly well during the 1880-1930 period. Had Halifax kept pace even with Montreal during that period it would have had about 300,000 people by 1930 and would probably be a city of well over 1,000,000 today.
To put things into perspective, in 1871 the City of Toronto had 46,000 people and by 1931 it had 631,000. During that period Halifax went from 30,000 people to 59,000. Saint John went from 29,000 to 47,000. That's the period when the Maritimes really fell behind.
I am getting these stats from this great site by the way: http://populstat.info/