Millions of drivers on the 90/94 expressway through the heart of Chicago have seen the huge Morton Salt “When it rains, it pours” sign painted atop the company’s warehouse. The company has left, music has taken over the space, but the billboard will remain. Morton Salt marketing executive Brian Bissell tells WGN’s Steve Alexander about the building’s history. And yes, it was built by the same Morton, Joy Morton, who created the Morton Arboretum.