Final answer:
Moonshiners shake the jar to check for impurities and alcohol content in their moonshine, with the behavior of the bubbles providing clues about the quality. Geographical remoteness and economic factors significantly contributed to the tradition of moonshining in Appalachia, which continues to this day.
Step-by-step explanation:
Moonshiners shake the jar to check for impurities in their moonshine. The shaking action causes bubbles to form, and the behavior of these bubbles can indicate the alcohol content and quality of the moonshine. A quick dissipation of bubbles generally signifies higher alcohol content, while slower-moving bubbles can suggest a lower alcohol concentration or the presence of unwanted substances. Historically, moonshining was a clandestine activity, especially prevalent in Appalachia during Prohibition. Moonshiners favored geographically remote locations to evade law enforcement and would often shake jars as a quick field test of their product's quality.
The history of moonshine is also closely connected to the Upland South's geography. Factors such as the mountainous terrain and isolation from major markets made it difficult for farmers to profitably sell crops like corn, leading them to distill it into corn liquor instead. These geographic and economic conditions, along with a significant Scottish and Irish ethnic heritage, contribute to the persistence of moonshining in these regions despite the end of Prohibition.