Walmart is open on Martin Luther King JR day.
Walmart doesn't close for holidays such as Martin Luther King Jr day or any other Federal holidays so they will remain open.
Some locally owned and operated grocery stores may be closed on Martin Luther King Jr Day but not all of them will.
Walmart does close on Christmas day though but on other holidays Walmart stays open.
I've been to Walmart shopping on Martin Luther King Jr Day when I needed to buy some groceries or other things.