For the case of Halifax and Dartmouth, their geography on their own looks rather similar to those of New York, New York and Sydney, Australia. All waterways of those three cases lead directly to oceans. So if the intention was to grow Halifax and Dartmouth bigger, there would not be shortage of experience in city management and development.Anyway, in Ontario, Hamilton, London and Windsor could have been bigger, and Halifax didn't grow as much as it possibly could have either. Two of those cities are separated from another reasonably large city by a narrow body of water -- Halifax and Dartmouth, and Hamilton and Burlington -- so there are possibilities to add those. Windsor and Detroit are also separated by a narrow body of water.