In 1975 I started work on a series of 18 photographic silk screens on canvas of freeway interchanges and bridges. These were shown at six institutions during 1976 as a bi-centenial exhibit. The sponsor was the Addison Gallery of American Art at Phillips Academy in Andover Massachusetts. The process is the standard four color process-Yellow, Magenta, Cyan and Black. The canvas sizes are 66"x46" and the image sizes are 60"x40". They have a 14 line half tone screen, which means there are 14 dots in a linear inch in the image. Each canvas is numbered in edition of 5. Some of the editions were not completed and some were printed with 1 or 2 artist proofs. There is a catalog which was published by the Addison Gallery of American art. I believe the catalog is currently out of print.