Things I didn't know about history: rubberized canvas car tops

Technological change has been a constant since the beginning of the industrial revolution. But what was a difficult technical challenge and what wasn't is sometimes difficult to remember in retrospect.

For example, this Shorpy photograph shows a street in 1935:

Even an airy open streetcar

The really step into the scene, go to the full size image on Shorpy.

Every car on the street, even that Packard limo in the lower right corner, has a rubberized canvas insert in the roof, pointed out by Dave, th...