Re: Why does newspaper tear more easily up and down than side to side?

Paper is made of fibers.  The fibers in newspaper are lined up more in the
up and down direction than in the side to side direction, so you have to
rip more of the fibers when you tear up and down, and this makes it harder
to tear.  I don't know for sure why the fibers have a preference for lining
up in one particular direction. Possibly this happens when the paper
is pressed out on rollers to remove water.  The rollers might align the
fibers in the direction they roll.