Ever spot a strange window on the bottom of a semi-truck's passenger door? Here's more about why these trucks have this ...

There are approximately 3.5 million semi truck operators in the U.S., according ... a center table-top with a bench seat on each side, into a flat bunk, via sliding and folding magic.

For one thing, a semi truck's rear is usually obscured, so a dashboard rearview mirror wouldn't do anything. Regular side view mirrors, meanwhile, are too small to properly reflect the truck's ...