Excellent point! Might help predict future elections.
Signs in general, not just homemade signs, might be a good indicator. On a cruise this year we sat in on a panel discussion of the Media Research Center group. I think it was Steve Moore who said that when the campaign first began he wasn’t sure about DJT, but was helping him. He and others had flown into a small city airport, then took cars to go to a rural campaign venue. Driving through the Heartland, “Trump” signs were everywhere, and there were very few “Hillary” signs to be seen. I believe he said that was when it occurred to him Trump had a great chance.