There aren’t many blue flowers out there, particularly compared to yellow or white, but we do have a few that bloom in our area in mid summer. An impressive one is the Ohio spiderwort, Tradescantia ohiensis. This is a relative of the common houseplant variety of spiderwort that is grown mostly for showy leaves, bearing only modest flowers that may be blue, pink, or white. There are 85 species in the genus and many horticultural varieties.
Ohio spiderwort, sometimes called bluejacket, grows to knee-high or belt-high, and likes full sun.
A related plant that blooms mid summer along roadsides and in disturbed areas is the Asiatic dayflower, or common dayflower, Commelina communis. This introduced plant likes moist habitats and prefers part shade. While it is not native, most people welcome it when they see it. It can be invasive, though, and tough to get rid of when it is in favorable habitat. Hand removal by pulling is effective, although seeds can remain viable in the soil for more than 5 years.