Hi Jacque, I actually believe thats a "G" in the box marking, leading me to believe its Glenshaw glass co, though I have never seen a rounded "G" in a square before.  Link below.  I have also added a link to the date codes for Glenshaw.
Good luck
 https://glassbottlemarks.com/bottlemarks-3/
 https://www.angelfire.com/pop2/collectorscorner/glenshaw.html