Neat bottle. I have a 6 1/2 oz Smile soda bottle. Mine says Festus Crystal Soda Co Festus MO on the bottom.
Illinois glass mark with a 9 on the left 6 on the right and 1 at the bottom. I haven't found much about the company.
I'm thinking prohibition when THAT was legal but the rot gut poisons being served were nearly intolerable, a fine mixer. Kind of a legal back bar bottle when about everything else was illegal. Everyone played their part at a speakeasy.
Just a guess though.