Most of the eastern and midwestern U.S. was hazy due to summer like conditions. There was smoke all around as well, including large plumes in eastern Canada continuing to blow smoke into Maine, smoke in western Canada, and fires in northern Mexico with smoke reaching south Texas. The NOAA HMS site summarizes these best. The Mexico and western Canada smoke plumes and U.S. haze can be seen in this big picture MODIS Aqua image (click on these images to see them better).
A close up of eastern Canada shows the large smoke plumes; also, the intense haze in Michigan and the Great Lakes. PM2.5 levels reached as high as 50 ug/m3 in parts of Michigan and Ohio.