I found mouse or rat dropping in the garage in our 'new' house. I cleaned it up thinking that maybe it was old. 

The other day I saw more droppings. 

The garage door faces the back alley where our trash cans are. There is about an inch or two of a gap between the floor and the bottom of the garage door. 

How do I seal this space to prevent vermin from entering the garage?

[![garage door][1]][1]


Note: the garage door swings up it does not roll up. 

  [1]: https://i.sstatic.net/bsM1w.jpg