The EIA has put together a graphic depicting net power flows in the US (not including HI and AK). The overriding theme of their data is that electricity flows south in the US. The EIA says that the largest energy flows often come from areas with predictably over-sized generation capacity. The Northwest’s generation capacity is outsized due to it’s hydropower resources and the Chicago region’s large exports are due to nuclear power from Exelcon’s Commonwealth Edison service area.
Of course, the EIA explains their own data better than we can, so you can read the full article on their website.