Final answer:
The 18th Amendment, or Prohibition, led to an increase in organized crime and illegal activities, despite its intention to reduce alcohol consumption and improve public health.
Step-by-step explanation:
The impact of the 18th Amendment, also known as Prohibition, was that it led to an increase in organized crime and illegal activities. Despite being intended to reduce alcohol consumption and improve public health, the amendment had unintended consequences. It created a demand for alcohol that was met by bootleggers and smuggling, with figures like Al Capone becoming notorious. The illegal production and distribution of alcohol grew, while enforcement of the amendment became problematic.