Bright flashing lights near Idaho/British Columbia border.Driving with my spouse from Spokane, WA to Eastport, ID border crossing and into Canada at around 10pm en route to Banff National Park, first time either of us had been in that area. We kept seeing flashing lights on the horizon between Yahk and Cranbrook in British Columbia, bright white like sheet/heat lightning but it was a cool, clear, cloudless night. Definitely not lightning and lots more flashes in a row than you'd expect from lightning. Also sometimes emanated from down low as though coming from down near the ground, which had a thin layer of fog across it in the low-lying areas. Made us think of swamp/marsh gas or "will o' the wisp" in folklore. We could only assume it was the Northern Lights but it was solid white and sometimes coming from down low instead of on the distant horizon which was freaky.When we got to the lodge where we stayed in Cranbrook the first night we asked the manager about it and whether it could be the Northern Lights. She looked absolutely perplexed and said no, you can't generally see the Northern Lights from here, she's lived there 10 years and never seen them. We asked if it could be swamp gas (ha!) and she looked at us like we were crazy and changed the subject. We never got to the bottom of it. Would love to know what it was!