Answer:
During a snow storm, Main Street is always plowed first.
Explanation:
Main and Street are both part of a name
as "main" could be a adjective to the noun "street" as well, another similar sentence could be
During a snow storm, the main street is always plowed first.
(The main street could have the name Bob's Alley)
Here, as neither "main" nor "street" are part of a name, no capitals required.
