Monday, November 12 is the official federal legal holiday comemorating Veteran's Day (which is Sunday November 11).
Falling just one week before most schools and many businesses take a day (or more) off for Thanksgiving, the list of what's open tends to be longer than the list of what's closed on Monday.
OPEN on Monday:
SEPTA operates on a regular weekday schedule for most regional rail and a modified weekday schedule for bus routes (meaning no extra school hour runs-mostly in the City of Philadelphia)
Most stores are open for normal Monday hours.