In cooperation with The University of Texas at Austin this OSeMOSYS model of the U.S-Canada electricity system supports decarbonization efforts towards both countries’ emission reduction goals. We calculate the generation mix and transmission pathways between Canada and the U.S. under 6 climate and trade policy scenarios. The necessary increase in emission penalties leads to increases in transmission capacity. The electricity system requires significant dispatchable, low carbon electricity to meet emission reduction goals. The flexibility of hydro resources is another major factor that is studied. The generation from variable and non-variable renewables and transmission increase nationally and internationally with specific investments in hydroelectric, wind and solar.