I appreciate that, Ramos, because I was actually a bit disappointed by my own answer. I couldn't find a photo of the building they are next to, which I thought would be more convincing and interesting than the warehouse in the background. And it should be possible because there are so many photos online of the Gateway District before it was demolished, and it's a rather small area.   Last night, some time after I had posted and was just closing all my open tabs, I started browsing through one of the more interesting photo sites related to downtown Minneapolis and came across a whole series on the building they are next to, the Ritz/Minnesotan Hotel (http://www.lileks.com/mpls/hotels/ritz/index.html). So the people in the photo were most likely Minnesota based tourists. And the plates most likely say 1935, not only because they appear to be sitting on a 1935 Chevrolet Master Delux, but also because the windows of the Minneapolis Post Office building are visible through the windshield of the car in top photo, and that building was completed in 1933. That feels more like a sufficiently exact answer to me. Other than, of course, who these people are.