The event is a fundraiser for the San Francisco Center for the Book.
This year's steamroller was a classic.
Printmakers carve gigantoid block prints which are inked and then "pressed" with the steamroller right on the street.
Here are a few of the prints:
There are printmakers selling their works at booths on the street.
You can also tour the Center and even play around with some of the presses.
Here's Kate printing a small piece.
You can find out more about the San Francisco Center for the Book at www.sfcb.org