Some things sure have changed in the last 77 years… No congestion? Not so much. Low tolls? Not at all. Sidewalk? Closed. 
Interestingly, despite this ad being post-amalgamation, all the old communities are still represented on the map of the Border Cities.
5 lanes? I have seen other old ads for the bridge making this claim, I always thought old car were larger.
Back when Cameron was a major route, and continued past Dougall. Before Ouellette connected to Dougall. Before the 401, E.C. Row, I-75, 94, & 96. The French spelling of Lake “Ste. Claire” is used, here. But it’s hard to imagine 5 lames PLUS an 8′ sidewalk. Sure cars in the ’30s were narrower, but they still must have been tight lanes. I did find this pic of the bridge, probably from around the time of opening, and there’s car lined up, 4-wide, plus room for another lane and the sidewalk.
http://www.courthousenews.com/2010/03/25/25878.htm
Uzzy, interesting article at the site you provided. The bridge company collects and retains all the tolls. And yet the bridge is poorly maintained. In my opinion, the company is doing minimal maintenance in anticipation of building their new span.
On another note, I believe that the map is dated. Highway 2 was rerouted in the early 30s and did not pass through Maidstone by 1937.