Bottles in the riverbank - Another Riverside Attraction?
Rectangular bodied bottles like this with recessed panels were used for either medicine or food. I associate this especially tall, skinny form with flavorings or extracts. My photo below is from a recent ebay auction - the packaging tells all.
Fortunately or unfortunately depending on one's perspective garbage often was dumped into rivers. Other items floated in floods, were buried for some time only to be revealed later by shifting river bank materials. I have heard heard a number of stories in recent years about snorkeling and scuba diving in rivers which have yielded some fairly good bottles.
Your bottle was machine made, but in a mold, in the early 20th century.