The GTA is made up of communities that are generally within 30 minutes of the Toronto boundaries.

The population of the GTA is almost 7 million and has a density of about 850 per square kilometre or 2200 per square mile.

Hamilton is just outside that area at about 45 minutes from Toronto. However, a new boundary area has been created to include Hamilton, the GTHA, Greater Toronto Hamilton Area.

The Hamilton area population is about 750,000 making the GTHA population at almost 8 million. That is almost the size of New York City.

More Info: en.wikipedia.org