Looking at the NOAA HMS Smoke and Fire Product (top left), the small red dots indicate groups of fires, while the light grey areas are smoke plumes. The main one spanning much of Canada and the northern continental United States is from the wildfires that continue to burn in the northwestern US and western Canada. The MODIS Aqua image (top right) shows highly elevated AODs in this region of smoke.
In the Grand Teton National Park at 5:15 MDT (middle left), the visual range is 43 miles. Comparing to the clear-hazy photo to the right, air visibility has been diminished in the area of the plume.
Furthermore, the EPA AIRNow combined AQI animation below also shows moderate AQIs over Southeast, with Unhealthy AQIs seen in the northwest United States and Canada. The current high AQI is in Cottonwood, ID and Twin Falls, ID (153). The area of these high AQIs correspond to the aforementioned wildfires, and has been the case for quite some time, the plume is affecting the air quality in the northern US and most of Canada with not a lot of change in sight.