Best bag for papers?

For the teachers that do paper assignments, what type of bag do you use to carry your paper assignments with you? Because of the lack of chromebooks at my school, I have to do most if not everything on paper, which me and my students aren't complaining too much about in all honesty. However, I want a good bag to carry all of the papers in, but my backpack is usually too full to carry them, and walmart sacks don't last very long. What type of bags/totes do you use that will last for a good while?