Mark would like to connect up to four monitors on his laptop. Can he connect two by USB? Leo says that it will work. There are a lot of USB monitors out there. But there may be a limit that the video processor can push pixel-wise. So it depends on your video card. Look at your specs. And if you are using an external GPU, you'll need a driver to do that as well. But don't go above 1080p. That'll help.
From the chatroom: The Dell D3100 Docking Station or the D6000 display adapter. Both use USB 3.1 and connect your laptop to up to three additional monitors from a single cable. Leo says that may be the way to go.