Final answer:
The specific time after which a city or county cannot restrict mixed beverage sales on Sunday is governed by local laws, which are influenced by historical temperance movements and community standards.
Step-by-step explanation:
The restriction of sales of mixed beverages on Sundays is typically governed by local or state laws, and these laws can differ greatly from one place to another. The context provided refers to historical temperance movements and laws regarding the prohibition of alcohol. While the exact time a city or county may restrict sales of mixed beverages on Sundays isn't stated in the information provided, it's important to note that this is often subject to local regulations which may be influenced by past temperance movements and current community standards. For instance, some localities might prohibit sales before a certain hour on Sunday mornings to respect the traditional Christian day of rest. To find the specific restriction time for a particular city or county, one would need to consult the local laws or ordinances of that area.