From the Madison Public Library clippings files: Monona Bay Causeway set to open in November 1967

July 29, 1967

Video by Retiring Guy

Related reading: 
Just Ask Us.  When was the John Nolen Drive causeway constructed?  (Wisconsin State Journal, 6/8/2015)
Lake Monona Causeway - Madison, Wisconsin,USA.  (Missouri University of Science and Technology)

The railroad causeway is much older.

Other clippings files posts:
City's first skywalk opens in 1966.  (10/8/2017)
Proudfit and Regent streets widening.  (9/30/2017)
Northport connector.  (9/30/2017)
Regent Street extension beyond Rosa Road, another bad idea left on the drawing board.  (5/27/2017) 
Drake Street extension, a bad idea left on the drawing board.  (5/26/2017)