Manitoba Hydro's major export market is the US, with ~10x more transmission capacity compared to SK.

Transmission capacity to SK is a 150MW. See here: https://www.gov.mb.ca/sd/environment_and_biodiversity/energy...

Out west, the provinces are not heavily interconnected, all prefer to sell to the US. Alberta is easiest to look at. Here is their real-time supply/demand report:

http://ets.aeso.ca/ets_web/ip/Market/Reports/CSDReportServle...

Interchange is at right. Couldn't find a source for interchange capacity in Alberta as transmission is not outright owned by the government like in MB.