The North American grid is one machine spanning two countries. When a line trips in one province, the lights stay on in a neighboring state because electrons flow across the border within seconds. That interdependence is the system’s greatest strength — and its hidden fragility.
Interties between Canadian and US grids serve three jobs:
Modern grids are designed with N-1 contingency: any single element can fail without causing a blackout. But the consequences depend on how dependent a region is:
| If this corridor drops… | …the immediate impact is |
|---|---|
| Quebec → New England | Tight reserves, price spikes, gas plants ramping hard. New England has no easy replacement for ~2,600 MW. |
| Ontario → Michigan/PJM | Local price jumps, slower but manageable. |
| BC → Pacific Northwest | Modest — the Pacific NW has its own hydro and imports from California. |
| Manitoba → Upper Midwest | Mid-continent reserves tighten, but multiple alternate paths exist. |
Model it yourself: the PowerTrip Blackout Simulator lets you cut any corridor and see which regions wobble.
The classic cautionary tale is the 2003 Northeast blackout, started by a tree contact and cascading line failures in Ohio — 50 million people lost power across the US and Ontario. The lesson wasn’t that interties cause blackouts, but that interconnection spreads failures as well as benefits. Cascading is managed by protective relays that deliberately island sections of the grid.
Not automatically. Protective systems island failures within seconds. But a large simultaneous loss (e.g., the entire Quebec intertie) would immediately tighten reserves in importing regions and could cascade if reserves are already low.
Mixed. Weather-related outages have increased, but forecasting, interconnection and demand response have improved. The grid handles daily stress well; the tail risks are growing.
Basics: water, flashlights, a charged power bank, a plan for medical devices, and knowing your region’s grid exposure. The Blackout Simulator is a good starting point to understand your region’s dependencies.