Final answer:
The Twenty-First Amendment allows cities and counties in the U.S. to set their own alcohol laws and maintain dry laws if they choose, repealing the nationwide prohibition on alcohol established by the Eighteenth Amendment.
Step-by-step explanation:
The constitutional amendment that allows cities and countries within the United States to set their own alcohol laws, including the option to remain dry on certain weekend days, is the Twenty-First Amendment. The Eighteenth Amendment, which was ratified in 1919, initially outlawed the manufacture, transport, and sale of intoxicating liquors, officially starting the era of Prohibition. However, in 1933, the Twenty-First Amendment was passed, repealing Prohibition and granting states the power to regulate alcohol within their borders. This change created a variety of alcohol laws across the country, including the existence of dry counties and the imposition of high sin taxes on alcohol to discourage its consumption, particularly in areas with a strong presence of conservative, anti-liquor religious groups like Baptists, Pentecostals, and Methodists.