2021: A combination of Ocean desalination, record droughts, and the near extinction of the Honey Bee, result in a world wide Famine, affecting even Canada which had become North America's breadbasket only a few years earlier.
2024: Food riots in Canada, and a nearly bankrupt government supported by loans from the US and the EU, leads to a complete breakdown of social order in many Canadian cities. Martial Law is declared in Montreal.
2025: Quebec closes its borders to protect its food supply. When the Canadian government orders the Province's leadership to step aside, Quebec secedes from Canada. A number of other Provinces quickly follow as a fight between them erupts over control of food supplies.
2027: The Canadian government collapses. The United States sends troops into Ontario to secure access to the Hudson Bay. Full scale war breaks out only when Eco Terrorists in what Americans refer to as "Canucka" (in reality a confederation between BC and the Yukon), destroy the Alaska Natural Gas Pipeline.
2033: US Vertical Farms in the North West and New England are completed, giving the nation's most densely populated areas access to a stable food supply. The last remaining rebels surrender if the US agrees to construct similar facilities in Canada's major cities. The US does so, but only after formally annexing Canada.