It had been a relatively warm day, for northern Minnesota in March. About 10 degrees above freezing. So the snowbanks melted a bit, and the water ran down the sidewalks like opportunistic creeks. And after the sun went down, the air got gradually colder. And the water got gradually frozen, layer by layer, from the bottom up.
Ask anybody who runs a skating rink -- that's the best way to freeze a rink, layer by layer, from the bottom up. You get a nice, solid layer of ice, with an extremely smooth surface, great for skating. Not so great for walking. Even worse for hobbling along with a cane.
Years back, I spent most of a year living in Florida. I also spent a couple of years living in New Mexico. Down south in the warm, there were a great many things I missed about my home town. Icy sidewalks weren't on the list.
Had my first slip-and-fall in about a year, that night. The last fall I took, I stepped in a gopher hole or something similar, fell flat on my face, twisted my ankle really badly, and ended up walking with a cane. Fifty isn't old, but it's old enough. This time, luckily, I didn't realize I was falling till after I was flat on my back. So I didn't really have time to tense up, and I landed as I said, flat on my back, spreading 225 pounds of force across the full width and length of my torso. No new injuries, just a bit shaken up. And I walked a lot more slowly and carefully the rest of the way to the store.
I bought myself some pastries while I was there. I deserved a treat.